Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2007
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Llansadwrn (Anglesey) Weather:
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Note: Values in (.) refer to the 10-y 1997-2006 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. Javascript must be enabled to see the pop-up graphics.
The beginning was wet and stormy with a colder spell from the middle of the month and a quiet and dry end.
The mean temperature of 6.9C (+1.4) and [+2.0] was the highest since before 1979 when temperature records were started at the station. The highest mean 9.7C was on the 13th while the lowest was on the 25th. The mean maximum 9.2C (+1.2) and [+1.8] was highest since 2002 and ranked 2nd. The highest 11.7C (-0.6) unusually occurred on 3 days, the 8th, 12th and 19th. The lowest 5.5C (+1.9) was on the 23rd and was flanked by 5.7C on the 22nd and 24th making these days the coldest of the month. The mean minimum of 4.6C (+1.6) and [+2.2] was also a record breaker exceeding by 0.1C the means of 1989 and 1990. The lowest minimum -0.3C (+1.7) was the only subzero air temperature of the month, and the winter so far. The highest minimum 9.0C (+0.2) did not break any records! On the grass there were 4 ground frosts, 9.8 days less than the decadal average. The lowest -3.4C was +2.7 of the average. Soil temperatures too were elevated, the 30 cm mean was 7.0C (+1.8C) and again was the highest on record here in January. Lowest were in a 5-day spell 23 - 27th when the temperature slipped below the 5.6C (42F) threshold thought necessary for plant growth.
It was a stormy month with 10 days of gales (RAF Valley reported 11). Two spells 9 - 13th and 18 - 20th had gales every day. At RAF Valley the mean wind speed (mws) for the month was 22.4 mph, ranks 2nd to the 26.8 mph recorded in 1974. On the 11th the reported mws was 36.3 mph, highest of the month. Mean speed of strongest gusts was 46 mph with the highest 77 mph recorded on the 18th. (For further details of the storms see the diary).
 "December & January gales on Anglesey 1942-2007.")
December 2006 and January 2007 combined had the highest number of gales (23) recorded on Anglesey since 1942. High positive anomalies seem to occur every 8 to 10 years and there has been an increase in number since the 1960's. December and January 2007 had the greatest positive anomaly of 13.6 (difference from the mean of 9.4). An increase in storminess is a factor that can be linked to climate change and is one of the factors, along with temperature and rainfall, predicted to increase in the future.
Rainfall was above average for the month although we did have a drier spell from the 21st to the end of the month. Rainfall totalled 136.2 mm (138%) and [141%] of average ranks 19th in records from 1929 and wettest since 2004. The wettest day was on the 16th with 15.3 mm and, although no fall got up to 25 mm, 8 exceeded 10 mm. There were 10 (+3.7) of 5 mm, or more. Raindays totalled 24 (+5.7) and wet days 20 (+6.2). Dry days numbered 4 (-4.3).
Sunshine recorded at RAF Valley was 58.5 h (Kipp & Zonen Instrument) this was 91% of the decadal average, but 107% of the climatological 1971-2000 average. There were 6 sunless days with another 11 having <= 1.0 h. The sunniest day was on the 25th with 7.5 h. It was somewhat cloudier, away from the west coast, here in the SE of the island close to the Snowdonia Mountains. There were 12 sunless days and an estimated 51.7 h of sunshine.
A month of contrasts. The beginning was brighter and cold with frosts while the end was duller, warmer and wetter.
A moderately dry month with rainfall 52.7 mm (50%) of the decadal average, but was [70%] of the 30-y average, nevertheless ranked 26th driest in records since before 1928. The last 10-years has seen some wet Februarys, notably 2002 that had 187.7 mm with 5 seeing over 100 mm. The wettest day was on the 10th and that only had 11.1 mm. There were only 4 (-2.2) dry days, however, and the number of wet days (1 mm, or more) 14 (+0.1) was average. Rain days (0.2 mm, or more) numbering 16 (-2.7) as well as days with 5 mm, or more, 3 (-4.3) were below average. The total hid the fact that the second 14 days having 32.6 mm was the wetter with the first half having 20.1 mm (see Table).
February 2007 ___________________________________________________________________________ Days Tx Tn Tm Gmin AF GF Soil30 Rain PI Sol ___________________________________________________________________________ 1 - 14 8.2 1.6 4.9 -1.6 4 10 5.3 20.1 11.1 82.9 14 - 28 10.6 5.3 7.9 2.8 0 2 7.3 32.6 14.8 77.0 ___________________________________________________________________________ 1 - 28 9.4 3.4 6.4 0.6 4 12 6.3 52.7 25.9 159.9 |
The month had a mean temperature of 6.4C (+0.5) and [+1.1) of average that was highest since 2002. The mean maximum was 9.4C (+0.8) and [+0.9} with the lowest 2.2C, continuing the contrast in the first part of the month on the 8th, and the 12.7C on the 20th was highest since 2003. The mean minimum of 3.4C (+0.2) and [+1.3] with the lowest -3.1 (-2.0) on the 7th. There was a big contrast in minimum temperatures, the mean for the first half was 1.6C while the second have was 5.3C. There were 4 air frosts, all in the first half. The 7th also saw the lowest grass minimum -7.8C (-2.7) , lowest since way back in 1986; there were 12 (-1.2) ground frosts in the month with 10 in the first half.
It was a fairly bright month with sunshine above average for February. At RAF Valley there were 80.6 h (103%) and [107%] of bright sunshine recorded on the Kipp & Zonen recorder, lowest since 2005, but ranking 28th highest on the Anglesey record since 1930. The sunniest day was on the 2nd with 8.1h. There were 5 sunless days but another 3 had < 1h sunshine. It was a little duller in Llansadwrn with 77.4 h sunshine. There were 5 sunless days.
Rainfall and temperature above average, but airfrosts continue to decline.
 "Winter rainfalls in Llansadwrn, Anglesey."){kind=small}
Rainfall was 406.6 mm and was largest since winter 1999/2000 with 482.4 mm. It was [141%] of the 1971-2000 average and (126%) of the decadal average. The wettest winter was in 1994/1995 with 510.3 mm and 9 winters have had 400 mm, or more, since before 1929/1930.
The mean winter temperature was 6.8C (+0.8) and [+1.6] of average and ranked 2nd highest since before 1979/1980. The mean maximum of 9.3C was (+0.9) and [+1.4] of average, again ranking 2nd only to 1997/98 with 9.4C. The mean minimum, ranking 3rd highest, was 4.2C (+0.7) and [+1.7] of average.
 "Winter mean temperatures 1979/80 - 2006/07 with linear regression."){kind=small}
The graph shows the mean temperatures and smoothed plot over the 28-years of station records. Fitted to a linear regression the temperature significantly increased over the period by 1.5C, an indication the warming trend that has taken place in recent years.
 "Winter mean temperature anomalies in Llansadwrn. Differences from 1979/80-200607 mean."){kind=small}
The histogram shows the mean anomaly (differences from the 1979/80 -2006/07 mean) over the same period. Since winter 1988/89 there have been 8 with an anomaly of +0.5C, or more.
 "Winter airfrosts at Llansadwrn 1979/80 to 2006/07."){kind=small}
The decline in number of winter airfrosts since 1979/80 has been remarkable. The graph shows the number of airfrosts over the 28 winters fitted to a linear regression line. This shows that the mean number was over 30 at the beginning and this has fallen to about 6 by 2006/07. If the current rate of decline continues then there could be very few frosts in most winters a decade from now.
It was the sunniest March since 2003 and 7th sunniest on the Anglesey record since before 1930. Sunshine recorded at RAF Valley totalled 149.0 h (124%) of the decadal average and [141%] of the 1971-2000 average. The sunniest day had 11.2 h on the 24th, but the 26th, 27th and 31st had over 10 h sunshine each day.
March was also drier than average, the 62.7 mm was (87%) of the decadal and [74%] of the 1971-2000 climatological average. The largest fall was on the 5th with 18.8 mm and was sufficient to bring soil moisture of 69% dry mass close to the saturated-water percentage for the local soil. Thereafter the month was drier and by the 31st had fallen to 61% and was surface dry on the afternoon of 2 April. There were 9 (-0.8) dry days and 17 (+0.9) raindays. Wet days were 11 (-0.1) and only 4 (-0.5) days with 5 mm, or more.
 "Potential evaporation in March."){kind=small}
Potential evaporation from the Piche evaporimeter housed in the Stevenson screen was 37.0 ml (equivalent to 37.0 mm of rainfall). Potential evaporation from the lysimeter was 18.5 mm and there was a potential water balance of 44.2 mm. The lysimeter experiences lower temperatures in the ground than the Piche evaporimeter in the air and partly accounts for the difference in totals. The lysimeter also collects dew and this is not taken account of in the calculation. Dewfall at the beginning of the month was high, but lessened through the month. A combination of rising temperatures and less dew accounts for the larger lysimeter PE towards the end of the month.
The mean temperature was 7.1C (-0.3) and [+0.3] and was highest since 2005. The mean maximum was 10.5C (-0.1) and [+0.3) with the highest maximum 16.8C (-1.4) on the 27th. The mean minimum was 3.7C (-0.4) and [+0.4] with the lowest minimum of -0.9C (+0.8) on the 21st. It was the only day with air frost and was below 0C was only 2.2 hours. There were more ground frosts, the 10 (-1.4) of average, and the lowest -5.2C (+0.5) was also on the 21st.
Hail was observed on 7 (+3.2) days, 5 days had ice pellets and 3 had snow pellets. Sleet or snow fell on 4 (+2.2) days.
A dry, warm and sunny month. Temperatures ran consistently above average and finished 2.7C above the 1971-2000 average. The mean was 11.3C (+2.3) and [+2.7] and was highest on record since before 1979 at this station. The previous highest means were 10.6C in 1987 and 10.3C in 2003, the only other into double figures. The +0.7C over the 1987 mean was remarkable. The mean maximum was 15.5C (+2.9) and [+2.7] with the highest 21.0C (+2.7) on the 14th, but the 15th also had 20.1C, both unremarkable as temperatures in the mid-20s in April have occurred (e.g. 23.2C in 1990 and 25.3C in 2003). The lowest maximum was 10.0C, this fell on the 3rd and was 2nd highest to 10.3C recorded in 1997. The mean minimum was 7.1C (+1.7) and [+2.7] of average. The lowest was 1.8C (+1.5) on the 4th, 2nd highest to 2.0C recorded in 2004, the month joined company with the other 12 air frost-free Aprils in the last 28 years. The highest minimum 11.7C on the 25th equalled that recorded in 1987. The lowest grass minimum -1.4C (+1.5) was on the 4th highest since before 1985, and there were 4 (-2.2) ground frosts. There were some frosty nights in low-lying areas and at RAF Valley 9 ground frosts were recorded (lowest -4.6C on the 4th).
With a total of 30.4 mm rain it was the driest April since 1984 that had 11.4 mm and ranked 8th driest since before 1928. The largest fall was 22.8 mm on the 23rd (75% of the month's total), and was mostly light rain having a duration of 20.6h. There were 19 (+9.9) completely dry days, 6 (-11.5) rain (>= 0.2 mm) days and 4 (-10.0) wet days (>= 1.0 mm).
Sunshine recorded at RAF Valley with the Kipp & Zonen instrument was 227.4 h (151%) and [145%] of average. An estimated equivalent 255.8 h sunshine might have been recorded on a Campbell-Stokes instrument (see notes below) and April could be the sunniest on the Anglesey record since before 1930. The sunniest day was on the 30th with 13.8h; 12 days had 10 h, or more. There were 3 sunless days.
Rainfall of 72.8 mm was (101%) of the decadal average, but [127%] of the 1971-2000 average. It was lowest since 2005, but ranked 26th wettest since 1928 and was 111% of the long-term average. With May 2003 (148.3 mm) and May 2006 (124.7 mm) distorting the 10-year average the long-term gives a better idea of wetness. Most rain fell on 2 days; the 16th had 16.3 mm and the 13th 13.5 mm some 40% of the month's total. There were 8 (-4.1) dry days, but there were another 4 with a trace and 0.1 mm. Rain days were 19 (+3.5) and wet days 17 (+5.8) while there were 3 (-2.1) with 5 mm, or more.
The mean temperature in the soil at 30 cm depth was 14.1C (+0.5). Potential evapotranspiration was 63.8 mm giving a water balance of 9.0 mm for the month. Soil moisture on the 19th was 52.4% and this was to fall to 43.2% by the beginning of June.
The mean air temperature 11.8C was (-0.2) and (+0.3) of average. It was highest since 2004 and ranked 11th since 1979. The mean maximum 15.3C (-0.4) and [-0.7] was equal with 2006 and highest since 2004. The first day, a carry over from the warmth of April, had the highest maximum with 21.8C (-1.8) and was the only day to have above 20C. The 23rd had 19.7C and a further 7 had 17C, or more. The mean minimum was 8.3C (+0.1) on the decadal but a large (+1.3) on the 1971-2000 average. It was highest since 2002 and ranked 6th. The lowest minimum was 3.5C on the 29th, but ranked 7th highest since 1979. The 2 ground frosts, -0.5C on the 29th and -0.6C on the 30th, were the latest recorded dates in May and the year at this station.
Sunshine duration recorded at RAF Valley was 203.7h (109%) and [105%] of the adjusted Kipp & Zonen average. It was sunniest since 2001 with the sunniest day on the 21st with 15.0h. There was 1 sunless day.
Rainfall and temperature close to average and 3rd sunniest on record.
 "Spring sunshine duration on Anglesey 1931-2007."){kind=small}
It was the third sunniest spring on the Anglesey record since 1930. Sunshine duration at RAF Valley totalled 580.1 h (+127) and [+124]. Using Kipp & Zonen adjusted sunshine data from Holyhead and Valley it was the sunniest since 1948 that had 594.9 h and 1942 that had 619.2h.
 "Spring rainfalls in Llansadwrn, Anglesey."){kind=small}
Spring rainfall totalled 165.9 mm and was lowest since 2004 (152.6 mm) and 22nd driest since 1928.
 "Spring mean temperatures 1979 - 2007 with linear regression."){kind=small}
The spring mean temperature was 10.1C (+0.6) and equalled that of 1990 (rank 2). The mean maximum was 13.7C (+0.8) ranking 7th and the mean minimum 6.4C (+0.5) ranking 3rd. The graph shows the mean temperatures and smoothed plot over the 28-years of station records. Fitted to a linear regression the temperature significantly increased over the period by 1C, an indication the warming trend that has taken place in recent years.
 "Spring mean temperature anomalies in Llansadwrn. Differences from 1979 - 2007 mean."){kind=small}
The histogram shows the mean anomaly (differences from the 1979 -2007 mean) over the same period. Including this spring there have been 3 (1989, 1998 & 2007) with a positive anomaly of 1C, or more.
It was the wettest June since 1998 here with a total of 122.1 mm (169%) and [184%]. It ranked 8th largest in records since 1928, but places in the Midlands (Coventry) and northern England (Sheffield) had exceptional rainfall totals seeing the most rain of any month on record and consequent severe flooding especially in the north. Rainfall in England and Wales overall, however, was not exceptional and close to extremes we have come to expect in wet Junes. We were lucky to have 11 (+0.8) completely dry days and rain on 18 (+2.2) days. Wet days numbered 16 (+5.2) and falls of 5 mm, or more, were 9 (+4.2). The largest fall was 23.8 mm on the 14th. With potential evapotranspiration of 61.4 mm the potential water balance was 61.0 mm. Airflow had an easterly component on 15 mornings and this led on the 25th to a complete reversal of the usual west to east rainfall gradient across North Wales and northern England (see diary).
The mean temperature of 14.6C (+0.5) and [+1.0] was lowest since 2004, but ranked 8th highest in records since 1979. The mean minimum temperatures 11.4C (+0.8) and [+1.9] although lowest since 2005 ranked 2nd, but the month did poorly for day maxima the mean of 17.9C (+0.3) and [+0.2] ranking 13th and lowest since 2002. The highest maximum on the 11th was 23.5C (-1.5) at the end of a 3-day spell seeing 20C, or more. Another 21.4C on the 19th brought the number of 20C, or more, days to 4 (-2 LTA), lowest since 2002 that had only 2. June's 1987 and 1991, however, had none. The lowest minimum 6.5C (+0.7) was on the 28th that also had the lowest grass minimum 2.9C (+0.3). Soil temperature at 30 cm was 16.7C (+0.7).
Sunshine duration at RAF Valley was 169.9 h (105%) and [101%) of the K&Z adjusted averages. Sunniest days had 14.8 h on the 11th and 14th and there were 4 sunless days. The derived sunshine duration at Llansadwrn (169.9h) matched the Valley total on this occasion. Global solar radiation averaged 14.38 MJ, highest was 27.37 MJ on the 6th and lowest only 2.08 MJ on the 25th, close to an average day in January!
With 120.4 mm of rain it was a wet July with (209%) and [190%] of average. It was wettest July since 1974 with the 10th largest total since 1928. The largest July rainfall in Llansadwrn was 171.2 mm in 1938. Parts of England saw four times their monthly average and had serious flooding. According to the Met Office Pershore College recorded 157.4 mm and Brize Norton 127.8 mm in the 48-hour period on 19/20th. Brize Norton recorded 101.0 mm of their total in a 7-hour period and Pershore College 134.8 mm in a 16-hour period. So with only 2 times the July average here we can count ourselves fortunate not to have had more! The wettest day was on the 20th with 24.5 mm while the 13th had 17.6 mm. Rain days (0.2 mm, or more) numbered 23 (+9.0) and wet days (1.0 mm, or more) were 21 (+10.8). The latter were the highest number at this station since before 1979. Days with 5 mm, or more, were 8 (+4.0), but there were 8 (-4.4) completely dry days scattered through the month with 3 consecutive days at the end.
The combined June and July rainfall total was 242.5 mm and ranked the 5th largest since 1929. It was the most since 1998 with 245.7 mm, but below the largest total of 317.2 mm recorded in Llansadwrn in 1938.
The mean temperature was 14.9C (-1.0) and [-0.7] of average, the largest negative anomaly of the year so far, and lowest since 2004 and 10th lowest since 1979. The mean maximum was 18.2C (-1.2) and [-1.3] of average, again lowest since 2004 and 8th lowest since before 1979. There were 5 days with 20C, or more, scattered through the month. The highest was 21.9C on the 31st and this was (-4.0) of the 10-year average and -7.4 of the long-term average. The lowest maximum 14.4C (-0.4) occurred on the 20th a wet and sunless day. The mean minimum was 11.5C (-0.8) and [-0.7] lowest since 2002 ranking 8th since 1979. The lowest minimum 7.9C (-0.5) occurred on the 30th which also saw the lowest grass minimum 2.2C (-2.9). The grass minimum was the lowest recorded in July at this station since 1986. The mean grass minimum 9.2C ranked 3rd lowest; 8.6C was recorded in 1989 and 6.2C in 1986.
Sunshine duration recorded at RAF Valley totalled 184.2 h (112%) and [108.7%] of average. The sunniest day was the 31st with 14.0h, but a further 10 days also had more than 10 h each day. There were 3 sunless days the 13, 20 and 21st. Being on the coast there was more sunshine than in Llansadwrn, estimated to be 166 h. Sunshine duration at Valley, every month so far this year, has exceeded the 30-year 1971-2000 average!
A very disappointing month, but we have seen several Augusts, and summers, like this one in the past. So nothing unusual, except we have got used to some warmer ones in recent years. Rainfall was 108.4 mm (123%) of the decadal and [135%] of the 30-y average. The largest fall was on the 14th with 41.0 mm, one of the largest falls in Britain on the day and the most recorded in August at this station since records started in 1979. The largest daily fall in Llansadwrn in any month was the 127 mm on 10th August 1957 during a thunderstorm and recorded in 3 hours duration. Falls of 5 mm, or more, in the moth were 6 (-0.2) while wet days. 1 mm or more, were 9 (-3.3). Rain days, 0.2 mm or more, were 13 (-2.5). Dry days numbered 7 (-2.6).
The mean temperature was 14.9C (-1.2) and [-0.5] the differences from average reflecting lower than decadal, but not so low again the 1971-2000 average. It was lowest since 1994 (14.7C) and ranked 10th lowest since 1979. The mean maximum was 18.0C, lowest since 1992 (17.4C) and ranking 8th lowest since before 1979. The highest maximum was 23.6C on the 5th, there were 5 days of 20C, or more, with 2 days consecutive (9-10). The lowest maximum was 13.6C, this on the 19th. The mean minimum was 11.7C (-0.8) and [+0.3] of average, lowest since 1994 (11.4C) and 12th lowest since 1979. The highest was 15.4C (-1.4) on the 4th and lowest 8.3C (-0.2) on the 8th. The lowest grass minimum was 4.5C (-0.2) on the 20th. Soil temperatures at 30 cm depth averaged 17.0C and was (-0.7) of the decadal average.
Sunshine duration at RAF Valley totalled 160.9 h (99%) and [98%], highest since 2005. The sunniest day was on the 26th having 12.7h, while the 22nd had 12.5h, the 8th 12.3 and the 2nd 12.0h. There were 3 sunless days. In Llansadwrn global solar radiation averaged 10.25 MJ / m2. The highest was 22.07 MJ / m2 on the 9th and the 8th and 22nd recorded over 20 MJ / m2 each, otherwise it was dull and 14 days saw less than 10 MJ / m2. There was no, or little sunshine (< 6 minutes), on 11 days. Estimated sunshine duration was 135.6 h, lowest since 2004.
 "Summer rainfalls in Llansadwrn, Anglesey."){kind=small}
Summer rainfall totalled 350.9 mm and was largest since 1985 (351.2 mm). It was was of the 8th wettest since records began in Llansadwrn in 1928. The wettest summer was in 1957 with 443.9 mm, but that included the record thunderstorm fall of 127 mm on the 10th August. The previous year, however, also recorded 416.7 mm - two 400 mm summers in a row! Other notable wet years were 1965 355.8 mmi, 1954 369.2 mm, 1938 388.2 mm and 1931 with 362.0 mm. So wet summers are not that unusual, particularly before 1970. In recent years we have enjoyed rather more dry summers than wet ones.
The beginning was dry and sunny with the highest temperatures; the end was very wet and had the lowest temperatures
The mean temperature was 13.5C and was -1.0 of the decadal average, but +0.2 on the 30-y average. The highest mean was 15.1C on the 6th; the lowest 9.1C on the 28th was the second lowest on record in September since 1979. The mean maximum 16.4C (-1.5) and [-0.6] of average was lowest since 2001 (16.1C) ranking 13th. The highest maximum 20.5C (-3.9) on the 6th was one of only 2 days having 20C, or more. The lowest maximum was 10.9C (-2.9) on the 26th and was the lowest maximum in September on record since before 1979, the previous lowest was 11.0C on the 15th in 1994. The mean minimum 10.6C (-0.6) and [+0.9] was lowest since 2003, but ranked 13th highest in the records. The lowest minimum was 6.0C (-0.6) on the 18th and this date had the lowest grass minimum 1.7C (-1.5). The mean soil temperature at 30 cm depth was 15.6C (+0.4).
Total rainfall was 118.7 mm (109%) and [129%] of the averages. There were 11 dry days (+2.0) and 15 (-2.0) rain days, those with 0.2 mm, or more. There were 13 +(0.2) wet days with 4 days with 5 mm, or more, (-3.4) of average. The wettest days was on the 20th with 43.9 mm, wettest since the 55.4 mm in 2003. It was combined as one event, around 09 GMT, with the 19 mm on the 21st. Total rainfall in the event was 62.9 mm; the rate of fall at its peak in the 30 minutes after 09 GMT was 23.6 mm per hour and resulted in flash floods in Beaumaris, Menai Bridge and Bangor. The month's rainfall ranked 26th largest since 1928 and wettest since 2004 that had 165.8 mm, the previous September (2003) had 159.7 mm.
Sunshine duration at RAF Valley was 117.5 h, (91%) and [93%] of the averages, lowest since 2004. The sunniest day was on the 7th with 12.2h, the 3rd with 10.5h was the only other day to have 10h, or more. There were 3 sunless days and a further 7 had 1h or less. In Llansadwrn global solar radiation averaged 8.15 MJ / m2, the highest was 16.57 / m2 on the 6th and the lowest 0.79 MJ / m2 on the 2nd. Estimated sunshine duration was 112.2h with 2 sunless days.
Dry and mild with some good sunshine, but several days scattered through the month were overcast and sunless
Despite 6 sunless days and another 3 with 0.3 h, or less, at RAF Valley it was the 5th sunniest October on the Anglesey record since 1931 (K&Z adjusted values). With 124.3 h sunshine duration (124%) it was sunniest since 1994 (130.2 h K&Z adjusted) and only a few hours behind the sunniest 134.8 h K&Z adjusted in 1965. The sunniest day was on the 4th with 10.0 h. It was somewhat cloudier in Llansadwrn with an estimated 102.3 h bright sunshine and 8 sunless days. Total global solar radiation averaged 6.90 MJ / m2, the brightest day was on the 6th with 11.94 MJ / m2 while the dullest on the 27th had 2.71 MJ / m2.
It was a dry month with rainfall of 51.1 mm (35%) and [46%] of the decadal and 30-y averages. It was lowest since 2003 and ranked 6th driest since before 1928. The wettest day was on the 27th with 16.4 mm. There were 15 (+7.9) dry days and 13 (-7.8) raindays. Wet days were 7 (-10.2) and there were 4 (-5.0) days with 5 mm or more.
The monthly mean temperature was 11.9C (+0.2) and [+1.4] and was lowest since 2004. It was the 6th highest since before 1979. The highest mean was 14.8C on the 12th and the lowest 8.6C on the 24th. The mean maximum temperature was 15.4C (+1.1) and [+1.6], lowest since 2004. The highest maximum was 19.7C (+0.1) on the 5th with the lowest 11.9C (+1.6) on the 25th. The mean minimum was 8.4C (+0.2) and [+1.1] and was again lowest since 2004. The highest minimum was 13.5C (+0.9) on the 12th while the lowest 2.7C (-1.0) was on the 24th. The 24th also had the lowest grass minimum of -1.2C (-0.9), the only grass frost of the month, the first since 30 May (-0.6C). The mean earth temperature at 30 cm depth was 12.5C, spot on the decadal average.
Winds were generally light and from the S'ly quarter with 7 calm days recorded at 09 GMT. The monthly mean wind speed at RAF Valley was 11.3 mph, lowest since 2003. The 28th was the exception that had strong W to NW'ly winds and a gusty trough late in the afternoon. A gale was reported at RAF Valley with a mean wind speed on the day of 20.3 mph and a maximum gust of 52 mph recorded.
The first half of the month was driest and warmest
Overall it was a dry month with a total of 85.8 mm rainfall (59%) and [69%] of average. It was driest since 1995 and ranked the 14th lowest since before 1928. The wettest day was on the 28th with 16.7 mm. There were 22 (-0.8) rain days (0.2 mm, or more) and 17 (-0.8) wet days (1.0 mm, or more). Days with 5 mm, or more, numbered 6 (-3.6). There were 5 completely dry days (+1.2).
The monthly mean temperature was 8.6C (+0.3) and [+1.3] of the averages, equal highest (with 2006) since 2003 and ranking 6th highest since before 1979. The highest mean was 13.2C on the first, one of 6, 10C or more. The lowest was 4.2C on the 24th. The mean maximum was 11.2C (+0.4) and [+1.2] highest since 2003. The highest maximum was 15.0C recorded on the 7th, 21 days had 10C, or more. The lowest maximum was 7.5C on the 23rd. The mean minimum was 5.9C (+0.2) and [+1.4], the lowest was -1.1C on the 24th and was the only air frost of the month. The highest minimum was 11.5C on the 1st. There were 9 (+1.3) ground frosts with the lowest grass minimum temperature -6.5C recorded on the 24th.
At RAF Valley 53.2 h of sunshine was recorded on the Kipp & Zonen instrument, 102% of the decadal average, but 93% of the 1971-2000 average. The sunniest day was on the 6th with 5.8 h and there were 6 sunless days. Mean global solar radiation in Llansadwrn was 3.14 MJ m-2, the maximum was 6.33 MJ m-2 on the 20th. Estimated sunshine duration in Llansadwrn was 63.8 h.
Autumn rainfall totalled 255.6 mm and was the least since 1995 that had 247.8 mm. Since observations started in Llansadwrn in 1918 it was the 10th lowest total recorded. Most of the period this year was drier than the total suggests, as up to the 26th November with a total of 219 mm rainfall, it had been the driest autumn since 1955 (202 mm) and the 3rd driest on record. Rainfall in the last few days of the month added another 34.6 mm and 7 places in the record table.
Temperatures were well above the 30-y [1971-2000] climatological average, but close to the decadal average. The autumn mean maximum was 14.3C (0.0) and [+0.7] and mean minimum 8.3 (-0.1) and +[1.1]. The mean 11.3C was (-0.1) and [+0.9].
The beginning was wet and windy, the middle dry sunny and cold with the end wet and windy once more
The mean temperature of 6.0C was (-0.1) of the decadal, but [+0.5] of the 30-yr average. This continuing, to the end of the year, the trend of increasing temperatures. The highest means were 11.3C on the 5th and 10.8C on the 6th, another also just reached 10C with 10.1C on the 28th. The mean was lowest since 2003. The mean maximum 8.7C was (+0.3) and showing the greatest anomaly [+0.8] of the 1970-2000 average. The highest maximum was 12.8C (+0.4) on the 4th, one of 12 days to pass the 10C threshold. The lowest was 3.7C (+0.5) on the 17th. The mean minimum 3.2C was the closest to normality with anomalies of (-0.1) and [+0.1]. There were 4 air frosts (+0.7) and a total of 54.7 h of frost. The 16th had the lowest minimum of -3.1C (-1.4) and recorded 19.2 h of frost in the 24-h midnight to midnight. The mean grass minimum was -0.6C (-1.4) and there were 18 days of ground frost (+4.7). Lowest was -8.2C (-0.7) on both the 16th and 17th.
Rainfall was 137.4 mm, lowest since 2005, and (103%) of the decadal and [120%] of the 1970-2000 averages. The wettest day was on the 27th having 21.8 mm. There were 10 days (+0.3) with 5.0 mm, or more, and 17 wet days (-0.1) both close to expected values. There were 18 rain days, those having 0.2 mm or more, this (-2.8) of average. Dry days numbered 10 and were (+3.6) of the average.
Sunshine duration at RAF Valley was 60.8 h (138%) and [141%] of the adjusted K&Z averages. It was sunniest since 2001 and the 10th sunniest December on the Anglesey record since 1930. This was remarkable considering the 9 sunless days, but can be attributed to the spell of sunny days 16th 5.8 h, 17th 5.9 h, 18th 5.8 h. 19th 5.9 h, 20th 5.8 h and 21st 5.9h. These were close to the maximum possible on Anglesey taking into account the delayed sunrise behind the Snowdonia Mountains in winter. Total global solar radiation measured at Llansadwrn was an average 2.41 MJ m-2, the maximum was 4.85 MJ m-2 on the 16th and the lowest 0.20 MJ m-2, and it was a very dull 'lights on in the house' day. Estimated sunshine duration in Llansadwrn was 57.2 h.
The annual mean temperature of 10.7C was (+0.2) and [+0.8] of the decadal and 30-y averages. Just 0.1C lower than the highest 10.8C recorded in 2006 and equalled that recorded in 1990 and 1997, so 2007 although equal second highest ranks 4th since before 1979 when records began here.
 "Annual mean temperature graph and regression equation."){kind=small}
 "Annual mean temperature anomaly (differences from the 1979-2007 mean)."){kind=small}
The graph shows the mean plotted over the 29-years of station records. Fitted to a linear regression the temperature increases over the period by 1.3C, an indication the warming trend that has taken place. The histogram shows the mean anomaly over the same period (differences from the 1979-2007 mean).
The annual mean maximum was 13.8C (+0.2) and [+0.4] of the decadal and 30-y climatological averages and ranked 8th; 2006 was 14.1C behind 1989 with 14.3C and 1990 with 14.4C. A feature of 2007 were the low maximum temperatures. The highest maximum of 23.6C on 5 August, failing to reach the 25C threshold, lagged well behind the 34.9C recorded on 19 July 2006.
 "No. days in the year exceeding 20C & 25C at Llansadwrn 1979-2007."){kind=small}
The number of days with 20C, or more, were just 20 in complete contrast to last year that reached 66 equalling the previous highest recorded in 1990. There were no days on which the temperature reached 25C.
The annual mean minimum 7.5C was (+0.1) and [+1.1] of average fell just behind the 7.6C of 2006, but with 1998 and 2005 becomes equal second highest (rank 4) . The lowest minimum was -3.1C on the 16 December and the lowest grass minimum temperature of -8.2C recorded on the 16 and 17 December (I did remember to reset it).
 "Annual rainfall statistics at Llansadwrn 1929-2007."){kind=small}
Rainfall for the year totalled 1100.7 mm (94%) and [107%] of average, lowest since 2003 and ranking 29th since before 1928. The total was well below the 1484 mm recorded in 2000, the wettest year on record, and 1999 that had 1286 mm. The wettest month in Llansadwrn was January with 138.2 mm closely followed by December with 137.4 while the driest was April with 30.4 mm. The greatest fall was 43.9 on 20 September. Rain days totalled 204 and there were 166 wet days. After a somewhat wetter 1950/60's and drier 1970's there has been a trend of increasing rainfall through into 21st Century
 "Annual Anglesey sunshine anomaly 1930-2007."){kind=small}
Following the sunniest year since before 1930 sunshine duration total at RAF Valley was 1590 h (Kipp & Zonen electronic instrument) (112% of average) equivalent to 1821 h had the Campbell-Stokes instrument still been in use. Just 59 h short of the 2006 record it was the fifth sunniest on the Anglesey record since 1930 using Kipp & Zonen corrected values.
The sunniest day was on the 21st May having 15.0h duration. There were 51 sunless days 3 less than last year. Estimated sunshine duration in cloudier Llansadwrn was 1431 h with 70 sunless days.
Llansadwrn (Anglesey): Monthly weather data for 2007.
~ Anomaly based on the 1997-06 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 9.2 9.4 10.5 15.5 15.3 17.9 18.2 18.0 16.4 15.4 11.2 8.7 13.8
Mean min 4.6 3.4 3.7 7.1 8.3 11.4 11.5 11.7 10.6 8.4 5.9 3.2 7.5
Mean 6.9 6.4 7.1 11.3 11.8 14.6 14.9 14.9 13.5 11.9 8.6 6.0 10.7
Anomaly~ +1.4 +0.5 -0.3 +2.3 -0.2 +0.5 -1.0 -1.2 -1.0 +0.7 +0.3 -0.1 +0.2
High max 11.7 12.7 16.8 21.0 21.8 23.5 21.9 23.6 20.5 19.7 15.0 12.8 23.6
Date 8,12,19 20 27 14 1 11 31 5 6 5 7 4 5 Aug
Low max 5.5 2.2 5.0 10.0 10.4 13.4 14.4 13.6 10.9 11.9 7.5 3.7 2.2
Date 23 8 20 3 27 25 20 19 26 25 23 17 8 Feb
High min 9.0 7.5 7.6 11.7 13.0 15.2 13.8 15.4 15.1 13.5 11.5 10.9 15.4
Date 13 1 11 25 24 11 16,26 4 6 12 1 5 4 Aug
Low min -0.3 -3.1 -0.9 1.8 3.5 6.5 7.9 8.3 6.0 2.7 -1.1 -3.1 -3.1
Date 25 7 21 4 29 28 30 8 18 24 24 16 16 Dec
Grass min -3.4 -7.8 -5.2 -1.4 -0.6 2.9 2.2 4.5 1.7 -1.2 -6.5 -8.2 -8.2
Date 25 7 21 4 30 28 30 20 18 24 24 16,17 16,17 Dec
Atmospheric moisture means
RH (%) 88 91 85 79 79 84 88 88 88 88 92 88 87
Dew point (C) 5.0 3.9 4.4 7.5 8.4 12.3 12.5 12.7 11.6 9.0 6.8 3.8 8.2
Soil temperatures (C)
5 cm 5.9 4.9 6.0 11.8 14.4 17.2 16.7 16.4 14.6 10.7 7.9 4.4 10.9
10 cm 6.2 5.3 6.1 10.7 13.0 15.8 15.8 15.8 14.2 11.0 8.4 4.9 10.6
20 cm 6.7 6.0 7.0 11.1 13.3 15.8 16.2 16.2 14.9 12.0 9.2 5.4 11.2
30 cm 7.0 6.3 7.7 11.6 14.1 16.6 17.0 17.0 15.7 12.5 9.6 6.0 11.8
50 cm 7.6 6.9 8.1 11.5 14.1 16.2 16.8 17.0 15.9 13.2 10.5 7.1 12.1
100 cm 8.5 7.7 8.6 10.8 13.3 15.0 15.8 16.2 15.7 13.6 11.5 8.7 12.1
Rainfall (mm)
Rain tot 138.2 52.7 62.7 30.4 72.8 122.1 120.4 108.4 118.7 51.1 85.8 137.4 1100.7
Rain % ave~ 138 50 87 39 101 169 209 123 109 35 59 103 93.5
Days, dry 4 4 9 19 8 11 8 7 11 15 5 10 111
Days >=0.2 24 16 17 6 19 18 23 13 15 13 22 18 204
Days >=1.0 20 14 11 4 17 16 21 9 13 7 17 17 166
Days >=5.0 10 3 4 1 3 9 8 6 4 4 6 10 68
Max fall 15.3 11.1 18.8 22.8 16.3 23.8 24.5 41.0 43.9 16.4 16.7 21.8 43.9
Date 17 10 5 23 16 14 20 14 20 27 28 27 20 Sep
Evaporation
Piche (mls) 29.3 25.9 37.0 52.4 50.1 39.2 31.3 36.4 33.8 27.8 21.5 26.7 411.4
Lysimeter PE (mm) 7.2 2.4 18.5 45.6 63.8 61.4 45.5 40.4 25.4 12.5 5.7 -6.9 321.5
Weather (days)
Air frost 1 4 1 0 0 0 0 0 0 0 1 4 11
Ground fr 4 12 10 4 2 0 0 0 0 1 9 18 60
Sl/snow 2 4 4 0 0 0 0 0 0 0 1 0 11
Sn lying 0 1 0 0 0 0 0 0 0 0 0 0 1
Thunder 1 0 0 0 0 0 1 0 0 0 0 0 2
Hail <5 mm 6 4 7 0 2 0 0 0 1 0 1 3 24
Hail >=5 mm 1 0 0 0 0 0 0 0 0 0 0 1 2
Fog at 09h 0 0 2 0 0 0 1 0 0 0 0 0 3
Gales 10 3 2 1 1 0 0 0 0 0 0 6 23
Wind direction at 09h (days)
N 1 2 2 2 3 1 1 6 3 0 3 1 25
NE 5 5 6 10 8 12 4 3 9 2 1 6 71
E 0 3 2 3 0 1 0 0 0 1 2 2 14
SE 0 5 1 1 2 2 0 2 1 4 2 2 22
S 4 5 4 7 5 6 10 8 6 5 5 9 74
SW 10 3 9 1 9 3 6 1 2 6 4 7 61
W 7 1 3 2 2 1 6 4 0 3 3 3 35
NW 4 2 3 1 2 3 4 5 2 3 6 1 36
Calm 0 2 1 3 0 1 0 2 7 7 4 0 27
Autographic records of rainfall and frost duration (h)
Rain 87.1 50.5 64.2 29.8 83.3 70.1 112.3 75.6 55.4 43.4 85.1 88.8 845.6
Frost 1.8 45.2 2.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4.5 54.7 108.4
Cloud cover at 09 GMT
Mean (%) 81 67 67 64 74 80 79 82 73 67 80 71 74
Global solar radiation (MJ m-2) and sunshine duration (h)
Llansadwrn
Sol rad mean 1.87 4.99 9.77 16.65 16.63 14.38 13.26 10.26 8.15 6.90 3.14 2.41 9.03
Maximum 5.36 9.17 18.46 24.60 27.15 27.37 22.22 22.07 16.57 11.94 6.33 4.85 27.37
Date 25 26 24 30 21 6 7 10 6 6 20 16 6 Jun
Minimum 0.19 1.71 2.35 4.74 5.92 2.08 4.01 2.33 0.79 2.71 1.15 0.20 0.19
Date 12 16 11 23 16 25 4 18 2 27 30 28 12 Jan
* ESD (h) 51.7 77.4 125.4 194.5 175.2 169.9 165.9 135.6 112.2 102.3 63.8 57.2 1431.1
Sunless days 12 5 4 2 4 3 3 11 2 8 7 9 70
Valley
Sunshine (h) 58.5 80.6 149.0 227.4 203.7 169.9 184.2 160.9 117.5 124.3 53.2 60.8 1590.0
Average % ~ 91 103 124 151 109 105 112 99 91 125 102 138 112
Sunniest 7.5 8.1 11.2 13.8 15.0 14.8 14.0 12.7 12.2 10.0 5.8 5.9 15.0
Date 25 2 24 30 21 7,9 31 26 7 4 6 17,19,21 21 May
Sunless days 6 5 2 3 1 4 3 3 3 6 6 9 51
# C-S (h) 62.7 86.2 160.7 255.8 241.9 205.9 221.1 189.1 134.6 139.3 58.3 65.5 1821.3
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
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Notes:
* ESD is an experimental Estimated Sunshine Duration. It was calculated using a relationship derived by fitting Llansadwrn global solar radiation and Valley sunshine duration data to a linear regression equation.
# 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. A conversion factor 1 has been applied to estimate what the Campbell-Stokes (C-S) duration might have measured for comparison. 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.
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 quoted Valley observations.
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These pages are designed and written by Donald Perkins © 2007: All Rights Reserved. Page first dated 5 February 2007 http://www.llansadwrn-wx.co.uk
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