Llansadwrn (Anglesey) Weather Latest Diary

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Times are GMT (UTC, Z). Observations at this station [ ] are 24-h 09-09 GMT, some others { } occasionally refer to other 24-h periods, extremes (first indications) are given in bold and are usually 21-21 GMT. When averages are referred to (.) compares with the last decade and [.] with the 30-y climatological average [currently 1971 - 2000]. All data are subject to verification and amendment.

Note: Updates to the diary from May to October may not be daily

Total rainfall for July was 182.1 mm, the largest recorded in Llansadwrn since records began in 1928. The mean temperature 15.7C was close to the averages (-0.1) and [+0.1] hiding the lower than average mean maximum 18.7C (-0.6) and [-0.8] and the higher than average mean minimum 12.7C (+0.4) and [+1.0] values. The highest maximum was 22.1C (-4.1). Sunshine recorded at Valley was 121.4 h (73%) and [72%], lowest since 2004 and the 9th dullest on the Anglesey record since 1930. The sunniest day was on the 3rd with 12.2h, there were 6 sunless days.

August

1st: After such a dull and wet July I have been asked if August be any better? Well it did rain on St. Swithin's Day so we can expect a wet month!. The statistics, however, show that it's about 50:50 based on an analysis of - is a July with greater than average rainfall {15 with >77 mm} followed by a greater than average {17 >101 mm}August? August on average is a wetter month and 7 of the last 10 have had over 100 mm! On the 1st day the sky was typically overcast, but was a little brighter at 09 GMT with the low stratiform cloud thinning a little. Some slight showers came along later in the morning and into the afternoon that was briefly bright, but no sunshine was seen. The evening was similarly dull with a little drizzle or rain at times. [Rain 0.5 mm; Max 16.3C; Min 12.2C; Grass 11.1C]
2nd: Overcast with a N'ly wind. Pressure was 1020 mb in a ridge of high-pressure extending from high 1035 mb over the Azores. Although keeping overcast the high pressure kept at bay an area of moderate to heavy rain over Ireland that slid S on a warm front associated with low 1000 mb S of Iceland. A patch of blue sky moved across during the afternoon, but there was no sunshine until 1715 GMT when there were some glimpses and a little more later in the evening. The sky was cloudy at 21 GMT. [Rain 0.2 mm; Max 16.1C; Min 11.6C; Grass 9.9C]
3rd: Little change, overcast with low stratiform cloud associated with an occluded front over Scotland, Anglesey and Pembrokeshire. The morning had some slight showers with glimpses of sunshine. With another frontal system approaching cloud thickened during the afternoon and evening and there was light to moderate rain from 2330 GMT. [Rain 10.7 mm; Max 17.5C; Min 12.0C; Grass 10.0C]
4th: Rain until 06 GMT then drizzle with rain showers up to 09 GMT when 10.7 mm was measured. Cloud was low on the mountains and visibility moderate. Drizzle or light rain continued eventually dying out during the morning that remained dull. The afternoon was brighter with a few sunny interludes developing later. Cloud continued to hug the mountaintops into the evening. At 2030 GMT the sky was becoming clearer. [Rain 0.1 mm; Max 16.6C; Min 11.4C; Grass 11.2C]
5th: A bright start, butt already cloudier by 09 GMT. There had been some clearer sky overnight and the grass minimum had fallen to 7.4C. We were in a showery WNW'ly airflow and clouds were piling up against the mountains and with the tops covered there were showers across the summits. There were frequent showers of rain in Bangor and SE Anglesey in the morning these lessened by noon. After a few spots the afternoon was brighter as cloud lifted and there was a little sunshine. Three red admiral butterflies together with a peacock and a comma were seen on Buddleia in the garden. The sky was mostly cloudy later and into the evening that kept dry. [Rain 0.3 mm; Max 18.3C; Min 11.2C; Grass 7.4C]
6th: With Atlantic-low 1000 mb approaching the Western Isles of Scotland, and a frontal wave with triple point over the Irish Sea and Anglesey, the day began dull and wet. There was drizzle from just before 07 GMT, moderate to heavy at times. Still overcast at 1030 GMT the drizzle had stopped and the cloud was thinner. The afternoon was breezy and dry so that washing dried, but there was no sunshine. The cloud thickened later and there was some drizzle during the evening. [Rain 4.6 mm; Max 17.5C; Min C; Grass C]
7th: Drizzle and light rain showers overnight tending to lessen, but still continuing up to 09 GMT. Pressure was 1013 mb with low 1007 mb over Scotland and the 'comma' frontal cloud over North Wales. Overcast with brighter spells and occasional glimpses of sunshine and slight rain showers dying out by afternoon. Brighter during the evening with the sky clearing a little by dusk at 2030 GMT. [Rain trace; Max 16.4C; Min 13.5C; Grass 13.1C]
8th: With a more or less cloud-free sky overnight the air temperature dipped down to 9.7C and on the grass to 5.0C. There was moderate dew and condensation on windows not seen for a while. Bright at first with variable amounts of cloud, some convective cumulus were dark, the brighter again. There was a very light SW'ly breeze so progress of cloud was slow. Pressure was 1022 mb in a ridge from Azores-high 1027 mb, but this was likely to be transitory. Complex shallow lows to the North, low 1009 mb S of Iceland had associated fronts poised W of Ireland threatening more rain. Chiffchaffs around the garden still give the odd burst of song from time to time. We have many tits visiting the feeders that have to be frequently resupplied. The afternoon was brighter and increasingly sunny with the temperature rising to 19.0C. Several more red admiral butterflies were spotted and were joined by the peacock, comma and small tortoiseshell. A sunny evening and mostly clear sky at 21 GMT. [Rain 3.6 mm; Max 19.0C; Min 9.7C; Grass 5.0C]
9th: Cloud had encroached by midnight, but rain kept off until 06 GMT when drizzle then moderate rain arrived. The rain was light at 09 GMT, but driving across the fields on the moderate SW'ly wind; visibility was very poor. Rain had stopped and the sky was looking brighter at 1030 GMT and soon some glimpses of sunshine. With the day then keeping dry, but mostly cloudy, the temperature rose to 20.2C. Scattered clouds continued through the evening. [Rain 1.4 mm; Max 20.2C; Min 12.2C; Grass 10.7C]
10th: The sky was overcast at 06 GMT then began to clear quickly with just 2 oktas cover at 09 GMT. There was a line of cumulus clouds that persisted over the Snowdonia Mountains through the day, with some lenticular altocumulus. Some patchy cloud moved across during the morning then cleared again by afternoon. It was a breezy, and after a few spots of rain in the morning a mostly sunny day, for the Anglesey Show with flags held tautly in the moderate to fresh SW'ly breeze. The show ground is adjacent to RAF Mona, where the temperature rose to 18.0C, used by Hawk trainers from nearby RAF Valley for landing and takeoff practice. There are traffic lights on the passing A5 that go to red when planes are coming in to land. It was a sunny evening with clear skies, but still breezy. [Coningsby 22.5C, High Wycombe 20.6 mm, Shawbury 9.5h, Valley 7.8h] [Rain trace dew; Max 19.0C; Min 11.7C; Grass 10.0C]
11th: Clear sky overhead early with the air minimum 9.5C and down to 6.1C on the grass. There was heavy dew and condensation on windows giving an autumnal feel to the morning. Cloudier (7/8) by 09 GMT, but bright with cumulus clouds over the mountains and slight rain on the radar over high high to the East. A family of swallows were chattering on the overhead electricity cable near the weather station. The afternoon was increasingly sunny and breezy in the moderate W'ly. The evening was mostly clear before cloud encroached again by midnight. [Rain 0.3 mm; Max 20.6C; Min 9.5C; Grass 6.1C]
12th: The sky was grey and overcast at 06 GMT and with low cloud edging in to the Menai Strait from the W drizzle, heavy at times, up to 09 GMT. Low 1007 mb was over the North Sea with high 1029 mb N Azores. An occluded front over the Irish Sea moved E triggering storms from Northumberland to Lincolnshire during the day. Heavy showers affected Northern England and a downpour during a thunderstorm in Greater Manchester during the afternoon caused flash flooding in Bramhall and part of the M60 near Prestwich. The drizzle petered out here leaving a mostly cloudy, but dry morning. The afternoon brightened and became sunny turning cloudier again during the evening. [Rain 0.1 mm; Max 16.4C; Min 11.6C; Grass 9.0C]
13th: The low 1009 mb over the North Sea was slow-moving off the Wash while pressure here 1022 mb influenced by the Azores-high 1031 mb stretching up to the W of Ireland. A not very promising mostly cloudy start gave some bright spells with glimpses of sunshine through to the afternoon and into the evening. By 21 GMT patchy cloud had moved over spoiling the chance of seeing Perseid meteors, debris from Comet Swift-Tuttle. Meteors were seen from Anglesey and Llanfairfechan when the sky cleared from the East about 11 pm. [Rain 0.2 mm; Max 17.0C; Min 11.4C; Grass 8.5C]
14th: The night was mostly cloudy with a light shower of rain at 0300 GMT, brighter after dawn, but cloudier once again up to 09 GMT. Pressure was 1021 mb with Atlantic-high 1028 mb W of Ireland and low 1015 mb over east Anglia. The morning continued mostly cloudy, but by afternoon with the sky clearing there was sunshine. The moderate to fresh NE'ly breeze off the sea gave a cool afternoon with the temperature rising to 16.8C. In the sunnier West the temperature rose to 19.1C at Valley. {Blackpool 22.2C, Hawarden 21.0C, Manston 37.8 mm, Leuchars 11.1h, Valley 10.4h} [Rain 0.0 mm; Max 16.8C; Min 12.7C; Grass 11.6C]

There were plenty of butterflies around on the banks of the Cefni Estuary. Peacocks (left), gatekeepers and meadow browns were frequent particularly seen on knapweed that is prolific this year. Along the edges of Newborough forest under some of the trees round-leaved wintergreen was abundant in places and here in close-up . .

The first 15-days had 22.0 mm of rainfall (22%) and [27%] of the August average. Drier than July, but with a potential water balance of 6.3 mm. The mean temperature was 14.8C (-1.0) and [-0.6] of the average for the month. Most noticeable were low maximum temperatures, the highest 20.6C on the 11th was (-4.3) of the average of the past 10-years.

16th: Pressure 1021 mb was falling and the sky was filled with cirrus clouds with a few small cumulus clouds pushed along on the light W'ly breeze. The morning was mostly sunny and with the W'ly instead of the cool NE'ly the temperature rising to 20.5C. By afternoon moderately high altostratus had encroached and there was weak sunshine at first. By 17 GMT the cloud had thickened and there were just glimpses of weakened sunshine. Rain fell over Ireland and W Scotland most of the day and eventfully reached her by dusk with light to moderate rain from 2030 to 2300 GMT. {Malin Hd. 19.1 mm} [Rain 4.7 mm; Max 20.5C; Min 11.0C; Grass 6.6C]
17th: Further drizzle and light rain, with moderate fog, from 0200 to 0900 GMT brought the rainfall to 4.7 mm. Stratiform cloud, on an occluded front, was low and visibility very poor with drizzle continuing for a while, with intermittent light rain, petering out by the afternoon. The temperature at 09 GMT was 16.0C (dewpoint 15.7C) and there was a light NW'ly breeze. The sky was slow to clear and we had to wait until 1625 GMT before the front had moved far enough eastward and for patches of blue to move across Anglesey. A line of cumulus, some towering, remained over the Snowdonia Mountains. Another cool day for August with the maximum temperature rising to 16.3C. The evening briefly sunny was cloudier by 21 GMT and overcast by midnight. {Hereford 24.4C, Mumbles Hd. 20.3C, Aultbea 20.8 mm, Hawarden 7.8 mm, Glasgow 8.6h, Valley 3.4h} [Rain 0.6 mm; Max 16.3C; Min 11.6C; Grass 11.4C]
¤ 18th: Overcast at first giving way to showery mostly cloudy skies at 09 GMT. The jetstream, positioned over southern Britain, and depressions continue to be generated to the West. Pressure here 1007 mb was declining in an unstable SW'ly airstream with a showery trough in the vicinity. There was a light shower just after 08 GMT and a heavy shower near the Menai Suspension Bridge and Four Crosses at 0950 GMT. By noon there was some sunshine breaking through and the afternoon was mostly sunny on Anglesey with, once again, showery cumulus clouds persisting over Snowdonia. The evening was mostly clear with bright stars visible. {Wisley 21.9C, Hawarden 19.4C, Lerwick 31.4 mm, At. Athan 4.2 mm, Aberporth 8.9h} [Rain 0.0 mm; Max 18.9C; Min 10.6C; Grass 8.3C]
19th: Clear sky after midnight with bright stars, turning cloudier before dawn when almost overcast. A weak ridge of high-pressure was declining and pressure was 1008 mb. Low 996 mb off S Ireland, tracking N, was winding up and pushing a warm fronton to the western seaboard. There was rain in SW England and this spread into Wales during the day reaching the N in the afternoon. The mountains gave Anglesey some protection at first, the first spots of rain here were at 1520 GMT. Light rain at first with some moderate bursts coming along during the evening. The Met Office issued a severe weather warning of heavy rain for most of Wales except Anglesey and parts of SE Wales. {Lake Vyrnwy 21.6 mm} [Rain 12.8 mm; Max 19.1C; Min 12.2C; Grass 9.8C]
20th: At midnight low 993 mb was off the Shannon Estuary, and an associated frontal system with triple point was over the N Irish Sea. Spells of rain, some moderate to heavy, through the night with a moderate to fresh S'ly wind. At 09 GMT under leaden skies there was a spell of heavy rain. Pressure was 1006 mb with the low 987 mb off the Western Isles of Scotland. Rain eased to drizzle then after a shower of rain about 1230 GMT ceased, but it took a while for the cloud to break doing so late in the afternoon the sunny spells going into the fine evening. {Weybourne 26.4C, Hawarden 24.2C, Capel Curig 39.2 mm, Manston 11.8h, Valley 2.0h} [Rain 1.5 mm; Max 18.4C; Min 14.2C; Grass 13.8C]
21st: A clearing sky at first with just 3 oktas cover at 09 GMT. Pressure 1015 mb had risen; we were on the edge of frontal cloud to the S where it was wet. Here keeping dry, with a mostly cloudy sky, occasionally bright. Towards evening as the front moved further S we had some sunshine lasting into the evening. {Weybourne 26.7C, Liscombe 21.6 mm, Mumbles Hd. 19.2 mm, Aviemore 10.1h, Valley 5.3h} [Rain 0.0 mm; Max 19.5C; Min 13.4C; Grass 12.3C]
22nd: Overcast with moderately high cloud at 06 GMT with most mountaintops in the clear. At 09 GMT the temperature was 16.6C (dewpoint 13.2C) and there were a few small cumulus clouds in the vicinity, but over the mountains to the S they were towering. Low 992 mb had mover over the North sea and was lying off the coast of Norway. The day was mostly sunny with few clouds and the temperature rose to 21.0C, but the evening was cloudier. {Cambridge 24.8C, Hawarden 21.8C, Plymouth 17.6 mm, Valley 11.8h} [Rain 1.9 mm; Max 21.0C; Min 12.4C; Grass 10.3C]
23rd: Back to overcast skies by the morning with light rain from 06 GMT turning showery then to drizzle. A glimpse of brightness at 1925 GMT did not last or develop into sunshine. Slight showers continued in to the afternoon, then a narrow slot of mostly blue sky passed over, but there were a few more spots of rain about 1545 GMT. Ripened grain is still standing on most of the fields hereabouts, being not dry enough to harvest. {Manston 23.1C, Milford Haven 18.4C, Monks Wood 42.6 mm, Pembrey Sands 14.8 mm, Camborne 9.2h} [Rain 0.2 mm; Max 15.8C; Min 12.2C; Grass 9.8C]
24th: Hints of broken cloud early suggested a fine morning, but a detached shower front, associated with an occluded comma front on low 982 mb S Norway, developed over Anglesey, the North Wales Coast and through Manchester across N England. A few spots of rain at 0900 GMT turned into moderate rain with heavy showery bursts up to 1100 GMT. By 1300 GMT the sky brightened and cleared soon after 1500 GMT with bright sunshine ahead of a frontal system heading SE giving rain over Scotland. A breezy day with the W'ly force 5/6 early decreasing force 3/4 in the afternoon when lines of cumulus clouds (cloud streets) were seen to the S over Snowdonia. There was a light shower of rain at 2030 GMT. [Rain 3.1 mm; Max 16.6C; Min 10.3C; Grass 8.0C]
25th: A promising start with thin moderately high cloud N of the Snowdonia Mountains with mostly weak sunshine and a light SE'ly breeze. Forecasts were for heavy rain in the S and the Met office were updating their warnings. Pressure here was 1013 mb with frontal wave low developing rapidly off Lands End bringing moist tropical air into the south-west. Rain was indeed heavy in the Scilly Isles {43.8 mm}, parts of southern Britain and South Wales {Mumbles Head 34.2 mm}; Flash flooding was reported in areas around Swansea and Gower. The storm tracked NE and, with the added protection of the mountains, rain kept away. At Penmon it was mostly sunny with patches of blue sky persisting over Red Wharf Bay until evening. Thicker cloud overnight, but no rain. {Gravesend 20.6C, Rhyl 17.7C, Scilly 43.8 mm, Mumbles Hd. 34.2 mm, Glasgow 10.5h, Valley 3.7h} [Rain 0.0 mm; Max 16.5C; Min 10.0C; Grass 7.4C]
26th: Overcast with the occasional brighter spell as thinner cloud passed over, but no sunshine. Pressure was 1008 mb and there was a moderate NE'ly breeze. [Rain mm; Max C; Min 12.1C; Grass 11.6C]

The Diary may not be updated daily from May to October

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Last month's diary Diary since January 2010 Daily Observations, usually updated bi-monthly Monthly summary and further analysis of the observations in 2009 Snowdonia snowline for 2009/2010, usually updated twice weekly in season The observer's choice of forecasts, satellite imagery and more Temperature graphs, daily and monthly rainfall histograms, accumulated rainfall total and more, all on a page for 2009 The Observer's Wx Bookshelf Location map and satellite image (use mouse, left click and hold to drag the image) A rare cloud-free image of the British Isles captured by the NOAA 12 satellite at 1623 GMT on 8 April 2002.

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