Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2005
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Llansadwrn (Anglesey) Weather:
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Note: Values in (.) refer to the 10-y 1995-2004 average; [.] refer to the 30-y 1971-2000 climatological average while {.} refer to the station LTA (long-term average) from 1979. All data are subject to verification and amendment.
The first half of the month was very mild and stormy with frequent gales, the second was quieter and cooler.
On the 16th temperatures were running 3C above average, and while the second half of the month was cooler the mean temperature of 6.6C was +1.2C but +1.7C compared with the [30-y] 1971-2000 average. The mean minimum temperature was 4.4C this +1.5C and [+2.0C]. The highest minimum was 8.6C (-0.1) on the 15th while the lowest was 0.7C on the 18th thus 2005 joins 1990 and 2000 as the only Januaries frost-free on the station's 27- year record. There were 5 days of ground frost (-2.7) with the lowest -2.2C (+4.8) seen on the 13th. The mean maximum was 8.8C +0.9C but a large [+1.4] on the 30-y average. The highest was 12.9C (+0.7) on the 7th. There were 10 days on which the maximum reached 10C, or more, 7 in the first half of the month. The lowest maximum was 4.7C (+1.4) on the 24th.
 "January mean temperatures and anomalies 1979-2005."){kind=small}
Effect of global warming in Llansadwrn: The top graphic shows a plot of the mean temperatures in January at Llansadwrn from 1979-2005. The calculated regression line indicates the warming trend (r=0.48) that has taken place and equates to a 2C rise in temperature over the 27-year period. The lower graphic shows anomalies from the 1979-2005 mean of 4.9C. It indicates the increased frequency of positive anomalies in recent years, another sign of the warming trend. Both the mean maximum and mean minimum data show similar trends and significance.
Rainfall of 109.8 mm was close to average (109%) and [112%], lowest since 2003 (82.2 mm). The wettest day was on the 7th having 51.6 mm, the largest fall recorded in January at this station, and nearly half of the month's total. Previous large falls were 40.6 mm in 2000 and 40.7 mm in 1984. The next largest fall this January was 9.0 mm on the 16th. There were 21 (+2.4) rain days, 0.2 mm or more, and 14 (-0.2) wet days, 1.0 mm or more. There were 8 dry days (+0.3). With the warmth and wind evaporation was more than average. PE (potential evapotranspiration) was 15.0 mm and was +12.2 (1997-2004) with PI (Piche evaporimeter) was 31.6 ml +3.7 (1996-2004).
 "January gales 1942-2005; Data courtesy Bob Jones Met Office RAF Valley."){kind=small}
It was a very stormy month with 11 days of gales with 10 of them, between 3 - 12th consecutive. Most winds (at 09 GMT) were from the SW (7 days) and W (7 days). The quadrant S to NW provided the wind on 22 days. At RAF Valley the mean wind speed (mws) for the month was 21.8 mph (+4.9) and (+6.2). On the 8th the mws was 40.9 mph while the highest gust of 76 mph was recorded on the 11th. An analysis of January gales since 1942 shows that this January was not the windiest. The most days with gales 16 were recorded in 1993; 1974 had 13 while 1984 and 1999 had 12 each, 1971 had 11 and 1957 and 1978 both had 10. January can be a stormy month; it has on average 4.8 days with gales.
Sunshine at Valley was 56.5 h (-8.5) and (-2.1). The sunniest day was on the 24th with 7.4 h just a little more than the 7.1 h recorded the previous day (23rd). There were 13 sunless days and another 4 had less than 0.2 h.
No thunder was heard in the month but small hail fell on 5 days (+0.8). Sleet fell on the 17th and snow on the 18th (-0.1).
Further reading: Global Temperature Trends: 2004 GISS (Goddard Institute for Space Studies)
Warmer and wetter first half then turning colder and wintry at the end.
 "February mean temperatures and anomalies 1979-2005."){kind=small}
The beginning of the month was warmer than average, by the 18th the mean was 6.1C (+0.3) and [+0.8] of the averages. At the end, following the spell of colder weather, the mean temperature finished on 5.0C (-0.9, 10-y average) and [-0.3, 30-y average]. Despite this the February 2005 had a small negative anomaly of -0.2 compared with the long-term 1979-2005 mean of 5.2C. Although February means in recent years have been lower, since the high of 7.9C in 1998, the warming trend continues (see graphic). The highest mean of 8.4C was on the 10th while the lowest of 1.9C was on the 24th.  "Number of winter (Dec to Feb) frosts in Llansadwrn 1979-2005."){kind=small}
Once again it is the minima that show the largest positive anomalies. On the 18th the mean minimum was 3.4C (+0.5) and (+1.3) and finished the month on 2.5C (-0.6) and [+0.4]. The highest minimum of 7.5C was on the 1st; the lowest of -1.0C was on the 16th, although the 28th was a close second with -0.9C. These were 2 of the only 3 days that had airfrost (-0.6). Since 1979 the number of airfrosts in the winter months (Dec to Feb) has been falling significantly (P<0.01), a consequence of the warming trend (see graphic). There were 14 ground frosts (+1.0).
Rainfall for the month totalled 74.0 mm and was 66% of the 10-y average. In the last decade February has had more than 100 mm on 5 occasions. These include the 3 consecutive wet years of 1998 - 2000. This has distorted the average; when compared with the 30-y (1971 - 2000) average the 2005 total is 99%. The wettest day was 20.3 mm on the 11th. There were only 2 other days, all in the first 11 days of the month, that got into double figures; 13.3 mm on the 4th and 12.5 mm on the 9th. There were only 4 dry days (-1.9). The month saw a large number of rain days (0.2 mm or more) 22 (+3.2), but the number of wet days ( 1 mm or more) were fewer 11 (-3.8) and similarly those having 5 mm, or more, were only 4 (-3.7).
The predominant wind direction, with 11 days at 09 GMT, was from the NE. The sector NW to NE had a total of 18 days whereas the sector SE to W had only 7 days. It was calm on 3 mornings. In contrast to January there was just 1 gale, on the 13th. At RAF Valley a mean wind speed of 28.0 mph was recorded with a maximum gust of 69 mph. It was windy too on the 12th, 14th and 24th. But overall the month finished below average; the 1 gale was (-3.5) and [-2.1] and the mws was 14.2 mph (-3.7) and -1.9].
Sunshine for the month was below average. At RAF Valley 71.7 h of sunshine were recorded, this being (-12.2) and [-9.0] of average. The sunniest day was on the 15th having 7.7 h but another 3 days had more than 5 h. . There were 3 sunless days and another 4 had less than 1 h.
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A month of contrasts, but at least for temperatures in the right order. The beginning was dominated by cold and drier N'ly winds while the end had mostly warm moister S'ly winds. The monthly mean was 7.9C +0.8 on the 10-y and +1.2 on the 30-y averages. The first 13 days average was 4.5C (-2.6) while the mean of the last 18 days was 10.8C (+3.7). The lowest maximum of 5.3C (-0.9) on the 2nd was lowest since 2001 with 3.8C, while the highest of 23.0C (+6.9) was on the 20th and was a record high for March at this station. The lowest minimum of -2.1 (-0.6) lowest since 2001 with -5.0C was on the 6th along with the lowest grass minimum of -6.2C (-1.8). The highest minimum of 12.2C on the 22nd was also a record high for this station in March. Total rainfall for the month was 52.4 mm, 81% of the 10-y average but only 62% of the 30-y average. The first 13 days were relatively dry with 10.8 mm, the wettest being on the 3rd with 6.0 mm. The last 18 days had 41.6 mm, the wettest day was the 30th with 17.6 mm while 14th had 11.5 mm. The month overall had only 5 dry days (-5.6), 19 (+3.8) rain days and 11 wet days (+0.8). With 103.2 h of sunshine recorded at RAF Valley it was the lowest since 1998 (76.3h) ranking 13th. The first 13 days were the sunniest with an average 4.2h per day and included 1 day with 9.9h. The last 18 days averaged only 2.7h but included the 2 sunniest days; 10.6 h on the 19th and 10.4 h on the 20th. Overall 13 days saw <1 h of sunshine, 4 of these were sunless. There were 6 days with all types of hail (+2.6), all in the first 13 days. The snow pellets that fell on the 3rd counted as large hail because they were >5 mm, they were perfectly conical-shaped and measured 9 mm. Thunder was heard on the 23rd. There was 1 gale in a month that had below average wind speeds. |
March 2005
Days 1-13 14-31 1-31
Maximum C 7.6 14.0 11.0
Minimum C 1.4 7.8 4.8
Mean C 4.5 10.8 7.9
Anomaly -2.6 +3.7 +0.8
Hi max C 9.4 23.0 23.0
Anomaly -6.7 +6.9 6.9
Lo min C -2.1 4.2 -2.1
Anomaly -0.6 +5.7 -0.6
Rain mm 10.8 41.6 52.4
% ave 17 44 81
hours 4.3 32.7 37.0
Wet days 2 9 11
Grass ave C -1.2 6.1 2.8
Anomaly -2.6 +4.7 1.4
lowest C -6.2 -1.6 -6.2
Soil 30 cm C 5.4 9.6 7.7
Anomaly -1.8 +2.4 0.5
Days hail 6 0 6
Air frost 3 0 3
Ground fr 10 1 11
Sunshine at
Valley h/day 4.2 2.7 3.3
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 "Llansadwrn rainfall anomalies November to March 1928-2005."){kind=small}
England and Wales have experienced the driest November to March period since 1975/76, each month having below average rainfall (Source Met Office). Here things have been a little different and the spell, with 456.1 mm, was the driest since only 1996/97 with 412.9 mm and 1995/96 that had only 253.9 mm. Since 1928 there have been 48 wetter November to March periods and 29 drier.
 "April rainfall anomalies at Llansadwrn, 1928-2005."){kind=small}
 "April rainfall totals, with smoothed average, at Llansadwrn, 1928-2005."){kind=small}
With 125.4 mm rainfall it was the 3rd wettest April on record since 1928. Based on the long-term average April, with 62.3 mm, is usually the driest month of the year. The wettest April was in 1970 with 142.1 mm while 1994 had 127.1 mm; only 6 previously had >100 mm. The wettest day was on the 5th having 27.5 mm but the 17th with 22.5 mm was not far behind. There were 24 (+7.9) rain days; 19 (+6.1) wet days and 7 (+1.9) had 5 mm, or more. The month did manage to accumulate 4 completely dry days, none consecutive. The graphics show (1) the differences from the 1928 - 2005 mean and (2) the totals with smoothed average. These show that there have been periods of higher and lower rainfalls in April since 1928. In particular the drier periods were from 1928 to 1945 and 1975 to 1985. Wetter Aprils were around 1945 to 1975 and from 1985 to the present.
The mean temperature was 9.0C and was on the past decade's average but [+0.4] of the 30-y average. Once again the mean maximum 12.3C was below average (-0.3) and (-0.5) while the mean minimum of 5.6C was above average (+0.3) and [+1.2]. The highest maximum on the 2nd was 20.1C and was (+2.1), than that date they were rather mediocre with the lowest of 5.9C (-1.9) on the 15th. The second highest was only 17.5C on the 22nd. The lowest temperatures were on the 9th, the air minimum 0.5) (+0.3) and above the grass -2.9C (+0.9). There were 3 ground frosts this (-3.1) of average.
It was a very dull month with only 125.8 h of sunshine recorded at RAF Valley (76% of the 10-y average and 71% of the 1971-2000 average). It was the 3rd lowest since records began in 1947. Last April was also dull with 119.8 h (dullest on record) and 1996 that had 123.2 h. Only 2 days had more than 10h sunshine; the sunniest day with 11.3 h was the 2nd and the 27th had 10.6h. There were 2 sunless days while another 6 had 1h, or less.
There were 6 days with hail (+2.4) and there was snow on the 8th. Thunder was heard on the 19th and there were 2 days with gales..
The beginning (days 1-15) was cooler and drier while the end (days 16-31) was warmer and wetter
A cool spell has kept the mean temperature for the first 15 days of month to 10.2C [-1.3] with the mean maximum on 13.9C [-2.1] and mean minimum on 6.5C [-0.5]. By the end of the month the mean temperature was 10.9C (-0.8) and compared with the 1971-2000 average was [-0.6]. It was lowest since 1996 (9.5C) and ranked 3rd lowest in records since before 1979, the other low year (8.8C). Another month was low maximums resulted in a mean of 14.5C (-1.1) and [-1.5]. The highest 19.4C on the 27th was (-4.3). It was lowest since 1996 (13.5C) and ranked 6th lowest on the station record. The mean minimum of 7.4C was lower than the average of last decade (-0.5) but [+0.4] compared with the 30-y average. Again it was lowest since 1996 (5.4C). The temperature of the soil at 30 cm also ran a little below average 12.9C (-0.5) in the first 15 days but was brought up to 13.2C (-0.2) by the end of the month.
Rainfall in the first 15 days was 19.5 mm, 34% of the 1971-2000 average, but when the month was completed the 57.8 mm was [101%] just (87%) of the last decade. A little wetter than 2004 (47.0 mm) but less than the 148.3 mm recorded in 2003. This year ranks 34th driest, there have been 45 wetter Mays since 1928. There were 8 dry days being (-5.1). There were 19 rain days (+4.7) and 12 wet days (+1.7). Four days had 5 mm, or more, the wettest was on the 23rd with 10.1 mm. Duration of rain (>0.1 mm per hour) was 48.6 h. Potential evapotranspiration was 52.7 mm so that the water balance was only 5.1 mm. The soil surface was dry on 9 mornings in 2 spells, 6 days 13/18th and 3 days 29/31st. Soil moisture levels were more than adequate but were down to 57% dry mass at the end of the month. The growth of grass (biomass production) started the month at 6.6 g per sq. m and fell to 4.2 g per sq. m on the 23rd. Grass growth this year, to the end of May, is some 30 % less than in 2004.
For the 5th month in succession sunshine has been below average. At RAF Valley sunshine totalled 210.8 h (93%) and [91%] of average. The sunniest day was the 14th with 14.5h with 10 days seeing 10h, or more. There was only 1 sunless day, the 18th while the 25th had only 0.1h. It was a very windy month. The monthly mean wind speed at RAF Valley was 15.8 mph the highest since January. Windiest days were the 19/20th with mws of 23.4 and 25.3 mph and 28/29th with mws of 25.7 and 25.8 mph.
Gales were observed in Llansadwrn on the 23rd and 28th. Thunder was heard on the 1st and 5 mm hail fell on the 17th and 4 mm ice pellets on the 23rd.
Temperatures were well above average with the mean 14.8C highest since 2003 and ranking 4th. The highest mean of 19.9C on the 18th ranked 6th highest and highest since the 20.8C in 2000. The lowest mean was 10.7C on the 12th and 13th was highest since 2003 and ranked 8th since 1979. The mean maximum temperature was 18.3C, was highest since 2003 ranking 7th. The highest maximum was 26.6C and ranked 5th highest in June, since 1979, and highest since 2000 that had 29.0C. The lowest was 10.7C and ranked 6th highest. The mean minimum was 11.3C, the highest on record at this station beating the 11.2C recorded in 2003. The warmest night was on the 19th with a minimum temperature of 17.6C, highest on record, beating by a long way the 15.9C recorded in 2003.
Rainfall for the month was 39.4 mm and was lowest since 2001. It was the 15th driest June in Llansadwrn since before 1928. Wettest day was the 28th with 12.5 mm and 3 other made more than 5 mm, 9.2 mm on the 1st; 5.0 mm on the 13th and 7.7 mm on the 30th (number of days >=5.0 mm was -0.8 of average). There were 14 dry days (+3.2), 12 (-3.5) rain days and 6 wet days (-5.0).
Sunshine recorded at RAF Valley was 179.6h and was below average (89%) [88%]. The sunniest day was on the 27th having 15.8h while the 26th had 15.1h and the 8th 15.0h with another 4 days having 10h, or more. There were 2 sunless days (16/17th) and another 4 had 0.2h, or less.
Thunder was heard on the 28th and 29th.
The month ended with 79.6 mm rainfall 133% of average [125%] and ranked 30th wettest since 1928. The wettest day was on the 27th with the 28th and 29th having 10.7 mm and 18.3 mm respectively. The 3 days of rain totalled 52.3 mm, 66% of the month's total. There were 13 dry days (+1.9) and 12 (-2.9) rain days (0.2 mm, or more). There were 10 (-0.3) wet days (1.0 mm, or more) while 5 (+0.8) days saw 5 mm, or more.
Temperatures were close to averages but generally a little above. The mean was 15.9C (+0.2) and [+0.3] highest since 2003; the highest 20.8C on the 12th and lowest 13.2C on the 25th. The mean maximum was 19.4C (+0.2) and [-0.1]; the highest 27.1C (+1.9) was on the 12th with 25.1C reached on the 17th and 25.0C on the 14th. In all there were 11 days that had 20C, or more in the month. The mean minimum was 15.9C (+0.2) and [+0.3]; the highest was 15.3C (-0.8) on the 11th. The lowest minimum of 9.2C on the 7th, was the only one below 10C in the month. The lowest grass minimum was 7.3C, also on the 7th, and the mean of 11.0C was (+0.6) of average.
Thunder was heard on the 27th.
Sunshine recorded at RAF Valley was 189.8h (102%) and [93%] of average. The sunniest day was on the 11th having 15.4h. In all 7 days saw 10h, or more, while 6 days had <1.0h. There were 3 sunless days (22, 29 & 30).
Sunshine has been recorded at Valley using a Campbell-Stokes instrument since 1946. This instrument used a spherical lens of clear glass to burn, when the sun was bright enough, a trace on a card. Uninterrupted sunshine produced a continuous burn on the card with tapered ends; the measurement was taken to the end of the tapers. When sunshine was broken the task was more difficult and allowance had to be made for exaggeration of the length of the burn. It was standard practice to measure from a point about halfway between the start and end of the taper. If there was hazy sunshine there was no spread of the burn and it was measured as far as it could be seen. It was a time consuming task requiring considerable interpretation and observational skill. Equipment has now been updated with the installation of an automatic Kipp & Zonen electronic instrument.
Rainfall of 71.8 mm finished 95% of average [89%] and ranked 27th driest since 1928. The wettest day was on the 23rd having 22.6 mm. Only 1 other day had double figures 11.9 mm on the 21st. There were 14 dry days (+2.5) and 14 rain days (0.2 mm, or more). Wet days (1.0 mm, or more) numbered 8 (-3.4) while 6 (+0.5) days had 5 mm, or more.
Temperatures were all below the average of the past decade, but were above the climatological 30-y average indicating the continuing trend.  "Number of days with maximum of 20C, or more, in Llansadwrn 1979-2005."){kind=small}
The monthly mean was 15.8C (-0.6) and [+0.4]; the highest was 18.7C on the 11th and the lowest 12.4C on the 26th. The mean maximum was 19.8C (-0.3) and [+0.5]; the highest 25.4C (-1.4) came on the 30th while the lowest 16.1C (+0.6) was on the 26th. There were 15 days on which the maximum was 20C, or more, +3.8 on the 1979-2004 average. There have been 4 peaks when consecutive August numbers have been greater than average, see graph, None have lasted more than 3 years, so 2006's number could be down! There is no statistical trend in these data. The mean minimum was 11.8C (-0.9) and [+0.4]; the highest 15.0C (-2.1) was on the 29th and the lowest 8.4C (-0.2) coming a few days before on the 25th. The 25th also had the lowest grass minimum of 5.7C (+0.3). Temperature of the soil at 30 cm averaged 17.4C, this was -0.4C.
Sunshine, recorded at RAF Valley using the Kipp & Zonen electronic instrument, was 194.5h (115%) and [119%]. It ranked the 6th sunniest August since before 1946 when records started. In all 5 days saw 10h, or more, and there was only 1 sunless day. The sunniest day was on the 8th and that had 13.1h. The mean wind speed for the month was 11.4 mph and was 110% of the past decade but only 93% of the 1971-2000 average.
The beginning of the month had record high maximum temperatures and plenty of sunshine. The rest of the month was rather changeable.
The 3rd had a maximum temperature of 26.6C, a record for September, but this was beaten the next day by 28.0C (+4.5). There were 6 days with a temperature of 20C, or more.
 "Monthly mean temperature anomalies at Llansadwrn (1979-2005)."){kind=small}
The month's mean finished on 14.8C +0.6 on the decadal average but +1.5 on the 1971-2000 average. The 4th had a daily mean of 21.9C a September record for this station. By the end of the month the daily means were lower and the 28th had the lowest 10.4C. The mean maximum was 18.2C (+0.6) and [+1.2] while the mean minimum was 11.5C (+0.7) and [+1.5]. The grass minimum temperatures averaged 9.2C (+0.7). The lowest was 1.5C (-1.6) on the 24th.
The beginning of the month saw plenty of sunshine with 4 days in the first 12 having 10, or more hours, recorded at RAF Valley. The sunniest day was on the 6th with 12.0h. It was the 20th sunniest September since before 1930 on the Anglesey record, sunshine duration totalled 137.0 (102%) [109%] with the sunniest day on the 6th with 12.0h. There were 4 sunless days, 9th, 15th, 26th and 30th while 6 others had <2.0h. Solar radiation totalled 311.7 mv h, the highest was 21.5 mv h on the 2nd while the 3rd had 19.4 mv h. Over the month 17 days had 10 mv h, or more while only 3 days had < 5.0 mv h.
Rainfall totalled 85.6 mm, this was 80% of the rainfall in the last decade that saw several rather wet Septembers. In comparison with the 30-y average it was 93%. It was the lowest since 2002, that was unusually dry with only 23.0 mm, before that it was 1997 with 69.4 mm. The wettest day was on the 28th with 13.1 mm. There were 8 dry days (-2.5) and 18 (+2.4) rain days (0.2 mm, or more). Wet days (1.0 mm, or more) were 14 (+2.1) but there were 8 days (+1.2) with 5 mm, or more.
Thunder was heard on the 4th but no hail was recorded. There was 1 gale on the 26th.
Some dry and sunny days spread through the month with heavy rain in between.
Rainfall of 212.6 mm was 163% of the decadal average and 189% of the 1971-2000 average. But it was drier than October 2004 that had 246.2 mm but was the 6th wettest October on record since 1928. The largest fall was 51.1 mm on the 11th while 33.5 mm fell on the 18th and another 32.5 mm on the 23rd. There were 7 (-0.1) dry days and 21(+0.4) raindays. Wet days totalled 16 (-0.6) and there were 10 (+1.4) that had 5 mm, or more, confirming a trend towards heavier falls.
Temperatures were all higher than average. The mean 12.8C (+1.6) and [+2.2] was highest since the 13.2C recorded in 2001 ( highest on record) and ranked third since 1979. The highest mean 19.3C on the 27th was highest on record. Three days in the month exceeded 20C; the mean maximum was 15.6C (+1.4) and [+1.8] equalled that of 2004, ranked 4th but fell short of the highest 16.0C recorded in 1995. The 27th, almost cloudless with 7.9h sunshine, saw some remarkably high temperatures in Northwest Wales with 24.1C (+4.7) recorded here, the highest in October on record. In contrast 16 days earlier on the 11th, the temperature could only rise to 11.7C and was the lowest of the month. The mean minimum was 10.0C (+1.8) and [+2.7]; the highest was 15.1C (+2.1) on the 30th and the lowest 5.5C was 16 days earlier on the 14th. The lowest temperature on the grass was 1.9C (+2.6) on the 14th; the zero number of ground frosts was 2 less than average. Soil temperatures at 30 cm averaged 13.1C (+0.7), range 14.0C on the 3rd to 12.4C on the 14th, but it was still 13.0C on the last day.
Thunder was heard on 2 days (+1.1) on the 11th and 25th and there was a fall of ice pellets on the 31st.
Sunshine recorded at RAF Valley totalled 78.8h and was (80%) and [83%] of average. It was lowest since 1989 and 10th lowest on record since 1946. There were 6 sunless days and another 6 had less than 1 h. The 15th was the sunniest with 9.4h when the temperature reached 22.3C in Llansadwrn.
Generally sunny with the beginning of the month warmer and wetter than the end
With 78.8 h of sunshine (88.3 h Campbell-Stokes equivalent) recorded at RAF Valley it was the sunniest November since 1993 (74.1 h Kipp & Zonen equivalent). Compared with the average of the last decade it was (138%) but was a little lower [127%] on the 1971-2000 climatological average. Since 1930 it ranked 8th sunniest on the Anglesey record. The sunniest day was on the 13th having 7.5h; other notable sunny days were the 1st 5.7h, 9th 5.4h, 21st 7.3h and 28th 5.7h. But there were 5 sunless days and another 9 had 1h or less, so it was not all roses.
The beginning of the month was the wettest with days 1-3 totalling 72.1 mm, the 3rd was the wettest day having 35.2 mm, but the 34.5 mm on the 6th was not far off. Rainfall for the month was 184.2 mm (137%) and [147%]. It was highest since 2003 (184.6) and ranked 9th wettest since 1928. It joins 54 other Novembers having 100 mm, or more. There were 4 dry days (0.1) and the 20 rain days (0.2 mm, or more) were -2.8 on the average. Wet days (1.0 mm, or more) were 18 and again close to average (0.1), so it was down to days over 5 mm numbering 11 to be above average (+1.7) confirming once again the recent trend being attributed to the effects of global warming. The total autumn (Sep - Nov) rainfall was 482.4 mm (130%) and [146%] ranked 7th wettest which was less than in 2004 (504.7 mm) and much less than the 612.1 mm recorded in 2000, the wettest on record.
Temperatures at the beginning of the month were running 3C above long-term average, were average in the middle and 3C below average at the end. The end result? Close to average, thus hiding the month's interesting variation. The mean was 7.5C (-0.7) [+0.2], the highest was 13.1C on the 3rd and the lowest 3.7C on the 28th. The mean maximum was 10.2C (-0.5) and [+0.2], the highest was 15.5C (+0.3) on the 2nd and the lowest 5.0C(-1.5) on the 28th. The mean minimum was 4.7C (-0.9) and [+0.2], the highest was 12.7C (+1.6) on the 3rd and the lowest 0.3C (-1.0) on the 19th. On the grass 12 frosts were recorded, +3.7 of average with the lowest -5.6C (-2.6) on the 19th. The mean temperature on grass was 1.8C (-0.9). The earth temperature at 30 cm closely followed the air temperature's fall had a mean of 8.8C (-0.2). There were no days on which the temperature was not above 5.6C (42F) the long regarded 'growing temperature' for plants. Looking at the autumn the mean temperature was 11.7C (+0.5) and [+1.3], the mean maximum was 14.7C and mean minimum 8.7C.
Evaporation measured by the Piche evaporimeter inside the Stevenson was 28.7 ml. The lysimeter recorded a negative potential evapotranspiration (PE) value of -4.0 mm. This can be attributed to inaccurate rainfall measurements as rainfall is used to calculate the value, and at this time of year more importantly dew and or frost deposition. In the latter case the raingauge can be said to be an inaccurate measure of the actual precipitation. Values of dew and or frost can amount to as much as 1 mm overnight during the winter months.
Thunder was heard on 2 days (+1.3) and hail fell on 8 days (+3.3). Large snow pellets up to 1 cm diameter fell overnight on the 24/25th resulting on up to 1 cm ice cover/ snow at 09 GMT on the 25th. Sleet or snow was seen to fall on 4 days (+3.2). There were 4 days with gales (7th, 11th, 25th and 26th).
In the first half temperatures were +1C with only 2 ground frosts, the second was colder with 3 air and 9 ground frosts
The mean temperature was 6.1C (+0.5 decadal) and [+0.6 1971-2000] of the averages. The beginning of the months saw highest temperatures; the highest mean was 9.4C on the 1st and the lowest 0.1C on the 28th. The mean maximum was 8.2C (+0.8) and [+0.3] with again the highest 11.5C (-1.2) on the 1st and the lowest 2.6C (-0.2) on the 28th. The mean minimum was 4.0C (+0.8) and [+0.9], the highest 8.7C (-0.1) bucked the trend and was on the 23rd while the lowest -3.3C (-0.9) followed a few days later on the 29th in the only cold spell (27-30) of the month. There were 3 airfrosts {-3.4 LTA} on the 28 - 30th when temperatures were below zero for 30.5 h. On the 28th the temperature was above zero for only 4.0 h reaching 2.6C about noon. There were 11 (-4.0) ground frosts, only 2 were in the first half of the month the remaining 9 in the second. The 11 were lowest since 1998, that had 10, and ranks 5th lowest since 1985 when records began. The highest number of December ground frosts 22 occurred in 1989 and 2001, the lowest 6 in 1988. The mean soil temperature at 30 cm was 6.5C (+0.3) and fell below 5.6C (42F) the long regarded 'growing temperature' for plants on the last 5 days in the month. The soil surface was frozen on 3 mornings (27-29) and on the 29th was frozen to at least 5 cm where the temperature at 09 GMT was -0.2C.
Sunshine recorded at RAF Valley totalled only 42.0h (45.3 h Campbell-Stokes equivalent) It was just 0.2 h more than 2004 lowest in December since 2000 (36.8h Kipp & Zonen equivalent). The average was 86% of the decadal average but 97% of the 1971-2000 average. It was the 24th dullest December since 1946 when records began at Valley. December 1998 with 23.3 h (25.1h by the Campbell-Stokes) has the record for the lowest amount of sunshine in any month. There were 12 sunless days with another 6 seeing <1 h. The sunniest day was on the 25th with 6.0h while the 12th had 5.9 h, but it was sunny too on the cold 28th that had 5.5 h. The only other notable (sunny) day was the 11th with 4.3h.
It was a dry month with 71.5 mm rain with both averages in agreement (63%) and [62%]. The 2 halves of the month had an equal distribution, but the latter half was biased because the wettest day on the 31st had 12.8 mm. Otherwise the rain was fairly evenly distributed most days having some rain with a little more at the beginning and, except for the last day, a drier end. The number of dry days was however only 4, (-3.1) of average. There were 5 days(-1.4) having 5 mm, or more.
Thunder was heard on the 3rd (0.3) and 3 days saw some hail (-2.4). Snow fell, moderately heavily for a while covering the ground, on the evening of the 29th, but in rapidly rising temperatures had melted before midnight. It was a quiet month with no gales recorded. At RAF Valley the mean wind speed of 13.1 mph was equal lowest since 2001/2002 and 10th lowest since 1956. The highest gust was 47 mph on the 1st with a monthly mean of 29.5 mph.
 "Plot of annual mean temperatures 1979-2005."){kind=small}
 "Annual mean temperature anomaly 1979-2005."){kind=small}
The annual mean temperature of 10.6C was 0.2C higher than in 2004 and (+0.1) of the decadal average, but was +0.7 when based on the 1971-2000 average. Equal highest since 2003 and ranked 4th since records started in 1979. The highest mean was 21.9C on the 4 September; the lowest was 0.1C on 28 December. There were 204 days with a mean of 10C, or more, the highest number on record, beating the 202 days in 1999. There were 75 days with 15C, or more, equal highest since 1997 but only 2 had 20C, or more (not unusual here). The histogram shows the mean plotted over the 27-years of station records. Fitted to a linear regression the temperature increases over the period by about 1C an indication the warming trend that has taken place in recent years. The other graph shows the mean anomaly (differences from the 1979 -2005 mean) over the same period. Since 1989 there have been 9 years with an anomaly of +0.5C, or more, 2004 with +4.5C just did not quite make it.
The annual mean maximum temperature was close to but above the averages 13.6C (+0.1) and [+0.2].  "Days with maxima >=15C, 20 C and 25C in Llansadwrn 1979-2005."){kind=small}
The highest 28.0C on the average (-0.0) was unusually on the 4th September and a record for that month (+4.5), the 3rd had previously broken the record with 26.6C. The lowest was 2.6C (+0.6) was on the 28th December.
There were 255 days on which the maximum was 10C, or more, and 158 had 15C, or more. The number of days with 20C, or more, were 47 and +8 on the LTA and close to the average, but were the most since 1999 (36). There were 7 days with 25C, or more, most since 2003 (8).
The annual mean minimum temperature 7.5C was (+0.3) and a large +1.1 on the 30-y average. While these data indicate a warming trend in recent years, a contributing factor again this year was the large amount of cloud cover at night acting as a blanket and minimising radiative cooling at night. The highest minimum was 17.6C (0.0) on the 19 June while the lowest of -3.3C (+0.6) was on the 29 December. There were 9 airfrosts, fewer than in 2004 that had 14 and lowest since 2002 (7) and ranked 4th lowest on record since 1979. The year was airfrost-free from 14 March to 27 December (288 days). Days with minimums less than 5C were 114 and less than 10C were 241. There were 56 ground frosts, less than in 2004 (67), and only 1 more than in 2002 (57) ranking 4th lowest since before 1985. The lowest was -7.5C recorded on 29 December. It was ground frost-free from 20 April to 6 December (230 days).
The change of sunshine recording instrument in August at RAF Valley # has meant a reassessment of duration averages. To enable comparison the January to July totals were converted to Kipp & Zonen equivalent values 1. With some very sunny months and some very dull months the year ended just under average for sunshine recorded. Total duration (K & Z equivalent) was 1335.8 h (94%) and [95%] of average. December with 42.0 hours had the least sunshine, but was 16.7h more than the 25.3 h (K&Z equivalent) recorded in November 2004. August was the sunniest with 194.5 h and along with July with 158.1h (102%), September with 137.0 h (102%) and November with 72.5h (138%) were the 4 months of the year with above average sunshine.
 "Annual sunshine anomaly at Valley, Anglesey, 1947-2004."){kind=small}
It was the 12th dullest year in records back to 1947. In the last 13 years there have been 4 dull years, but it was necessary to look back to 1958 with 1203.3 hours for the dullest. The graphic shows sunshine anomalies, differences from the 1947-2006, using Campbell-Stokes data to July and estimated August to December values. The 2006 anomaly, with August to December estimated equivalent values, was minus 84 h based on an overall mean of 1620 h.
 "Annual rainfall statistics at Llansadwrn 1929-2005."){kind=small}
Total rainfall for the year was 1164 1 mm (105%) and [113%] of average, lowest since 2003 (1008.5 mm) and ranking 24th wettest since 1929. There were 7 months drier than average and 5 wetter. Wettest were October with 212.6 mm (163%) and November with 184.2 mm (137%). For the time of year April with 125.4 mm (187%) was unusually wet and December with 71.5 mm (63%) unusually dry. January with 109.8 mm (109%) had the wettest day on the 7th with 51.6 mm, but October 11th had 51.1 mm. Other notable falls were 35.2 mm on the 3rd November and 27.5 mm on the 5th April. Throughout the year there were 93 (-16) dry days and 219 (+12) rain days (0.2 mm, or more). There were 153 (-4) wet days (1.0 mm, or more) and an average 75 days on which 5 mm, or more, fell. An average 32 10 mm falls occurred and there were 7 (+3) falls of 25 mm, or more.
 "Water dynamics at Llansadwrn, Anglesey in 2005."){kind=small}
The water dynamics graph shows the distribution of rainfall through out the year and the evapotranspiration (PE) that occurred. Rainfall was an uneven distribution, but PE follows a more even trend of high in summer, when temperature and sunlight is highest, and low in winter when they are not. The third curve shows the water balance and indicates that for most of the year water is in excess. ; "Soil moisture percentage (% dry mass) in 2005."){kind=small}
The exception was late in May and June when there was a negative water balance. Soil moisture was lowest in July when it fell to 30% (dry mass) in contrast to the close to the 70% saturation levels from January to April and again in October and December. The growth of grass was affected by the low moisture levels and was greatest in April (7.8 g per square metre per day) and September (7.1 g per square metre per day) . ; "Growth of grass in 2005: Red graph is total accumulated biomass; green is rate of production."){kind=small}
In the second part of July for a brief spell the grass did not grow at all. Over the year the amount of grass produced at the station
1088 g per square metre some 40% less than in 2004. As a result much less grass was available locally for making silage and hay this year.
Thunder was heard on 12 days, 1 less than 2004. There were 42 days with hail (all types) highest since 2000 (45) and ranks 2nd on record. These included 3 days with hail 5 mm, or more diameter. The snow pellets that fell on the 3rd March were perfectly conical-shaped and measured 9 mm.
Large hail fell on the 17th May and snow pellets up to 1 cm diameter fell overnight on the 24/25th November resulting on up to 1 cm ice cover/ snow at 09 GMT on the 25th. Sleet or snow fell on 19 days, the most since 2000 (19) and 1996 (22) but there were only 2 days with lying snow or ice cover. There were gales on 24 days.
Llansadwrn (Anglesey): Monthly weather data for 2005.
(~ Based on the 1995-04 average)
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
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Air temperatures (C)
Mean max 8.8 7.5 11.0 12.3 14.5 18.3 19.4 19.8 18.2 15.6 10.2 8.2 13.6
Mean min 4.4 2.5 4.8 5.6 7.4 11.3 12.4 11.8 11.5 10.0 4.7 4.0 7.5
Mean 6.6 5.0 7.9 9.0 10.9 14.8 15.9 15.8 14.8 12.8 7.5 6.1 10.6
Anomaly~ +1.2 -0.9 +1.2 0.0 -0.8 +1.1 +0.2 -0.6 +0.6 +1.6 -0.7 +0.5 +0.1
High max 12.9 10.6 23.0 20.1 19.4 26.6 27.1 25.4 28.0 24.1 15.5 11.5 28.0
Date 15 10 20 2 27 28 12 30 4 27 2 1 4 Sep
Low max 4.7 3.6 5.3 5.9 10.5 13.7 14.6 16.1 12.7 11.7 5.0 2.6 2.6
Date 24 24 2 15 17 12 31 26 16 11 28 28 28 Dec
High min 8.6 7.5 12.2 9.3 12.0 17.6 15.3 15.0 16.2 15.1 12.7 8.7 17.6
Date 10,15 1 22 28 28 19 11 29 5 30 3 23 19 Jun
Low min 0.7 -1.0 -2.1 0.5 3.4 5.8 9.2 8.4 5.0 5.5 0.3 -3.3 -3.3
Date 18 16 6 9 11 13 7 25 24 14 19 29 29 Dec
Grass min -2.2 -5.0 -6.2 -2.9 0.2 3.4 7.3 5.7 1.5 1.9 -5.6 -7.5 -7.5
Date 13 28 6 9 11 13 7 25 24 14 19 29 29 Dec
Atmospheric moisture means
RH (%) 89 87 86 84 78 83 81 85 86 88 88 89 85
Dew point (C) 4.8 2.3 5.4 6.0 7.5 12.0 12.8 13.2 12.4 10.2 5.1 4.2 8.0
Soil temperatures (C)
5 cm 5.4 4.0 6.9 9.3 13.4 17.1 18.6 17.1 14.8 11.8 6.5 5.0 10.8
10 cm 5.7 4.5 6.8 8.9 12.2 16.0 17.5 16.3 14.6 12.0 7.1 5.5 10.6
20 cm 6.2 5.4 7.3 9.4 12.5 16.0 17.8 16.8 15.3 12.5 8.1 6.1 11.1
30 cm 6.4 5.8 7.6 10.1 13.2 16.1 18.0 17.4 16.1 13.2 9.0 6.5 11.6
50 cm 7.0 6.5 7.7 10.2 13.1 15.7 17.7 17.3 16.3 13.5 9.9 7.3 11.9
100 cm 7.8 7.5 7.8 10.0 12.2 14.3 16.4 16.4 15.9 13.8 11.3 8.6 11.8
Rainfall (mm)
Rain tot 109.8 74.0 52.4 125.4 57.8 39.4 79.6 71.8 85.6 212.6 184.2 71.5 1164.1
Rain % ave~ 109 66 81 187 87 54 133 95 80 163 137 63 105
Days, dry 8 4 5 4 8 14 13 14 8 7 4 4 93
Days >=0.2 21 22 19 24 19 12 12 14 18 21 20 17 219
Days >=1.0 14 11 11 19 12 6 10 8 14 16 18 14 153
Days >=5.0 6 4 3 7 4 4 5 6 8 10 11 7 75
Max fall 51.6 20.3 17.6 27.5 10.1 12.5 23.3 22.6 13.1 51.1 35.2 12.8 51.6
Date 7 11 30 5 23 28 27 23 28 11 3 31 7 Jan
Evaporation
Piche (mls) 31.6 28.3 35.1 37.5 53.6 39.7 45.3 37.9 38.3 39.8 28.7 18.9 434.7
Lysimeter PE (mm) 15.0 14.6 18.6 31.2 52.7 59.7 57.1 43.7 23.4 16.8 -4.0 -6.4 322.4
Weather (days)
Air frost 0 3 3 0 0 0 0 0 0 0 0 3 9
Ground fr 5 14 11 3 0 0 0 0 0 0 12 11 56
Sl/snow 3 8 2 1 0 0 0 0 0 0 4 1 19
Sn lying 0 1 0 0 0 0 0 0 0 0 1 0 2
Thunder 0 0 1 1 1 2 1 0 1 2 2 1 12
Hail <5 mm 5 11 5 6 1 0 0 0 0 1 7 3 39
Hail >=5 mm 0 0 1 0 1 0 0 0 0 0 1 0 3
Fog at 09h 0 0 1 0 0 0 0 0 0 0 0 0 1
Gales 11 0 1 2 2 0 0 2 1 1 4 0 24
Wind direction at 09h (days)
N 3 4 6 2 4 3 3 6 2 2 4 4 43
NE 4 11 4 5 6 5 11 0 3 1 5 6 61
E 0 0 4 2 2 1 2 1 0 3 1 1 17
SE 0 1 1 2 0 2 1 0 3 7 2 4 23
S 4 1 6 7 8 10 4 9 9 9 7 4 78
SW 7 3 3 6 4 6 2 5 4 2 3 5 50
W 7 2 1 3 3 2 4 5 4 1 4 2 38
NW 4 3 3 3 2 1 3 5 2 3 4 3 36
Calm 2 3 3 0 2 0 1 0 3 3 0 2 19
Autographic records of rainfall and frost duration (h)
Rain 61.6 54.3 37.0 105.0 48.6 18.0 34.0 44.2 49.6 95.8 97.3 58.5 703.9
Frost 0.0 17.1 11.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 30.5 59.1
Cloud cover at 09 GMT
Mean (%) 79 79 76 82 78 77 78 82 75 81 73 77 78
Solar radiation total (Llansadwrn) and sunshine duration # (Valley)
Sol rad (mv h) 66.1 153.5 294.2 408.0 623.7 571.6 561.5 506.4 311.7 178.8 90.4 47.0 3812.9
Sunshine (h) C-S 56.5 71.7 103.2 125.8 210.8 179.6 189.8 228.6 156.9 88.3 79.5 45.3 1536.0
Sunshine (h) K&Z 52.7 67.0 95.7 111.8 177.5 148.2 158.1 194.5 137.0 78.8 72.5 42.0 1335.8
Average % ~ 90 85 79 76 93 89 102 115 102 80 138 86 94
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
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Notes:
# Valley sunshine duration, since August 2005, has been measured using a Kipp & Zonen electronic sensor. This gives sunshine durations that are different to the previous Campbell-Stokes instrument. Conversion factors 1 have been applied to estimate what the Campbell-Stokes (C-S) duration might have measured from August to December, and the Kipp & Zonen from January to July. The electronic sensor measures less sunshine than the Campbell-Stokes instrument, it varies throughout the year and is about 20% less in summer and 7% less in winter. Averages have been computed using estimated equivalent Kipp & Zonen sunshine durations as it seems this will be the instrument of choice in the future.
References
1: Prior J. (2006). Sunshine measurement. Weather 61, p. 77.
2: Kerr A. & Tabony R. (2004). Comparison of sunshine recorded by Campbell-Stokes and automatic sensors. Weather, 59 (4), pp. 90-95.
I am grateful to Robert Jones, Observer/ Admin. Officer at the Met Office RAF Valley, for supplying the Valley data.
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These pages are designed and written by Donald Perkins: Copyright © 2005 Page first dated 2 February 2005 http://www.llansadwrn-wx.co.uk
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