Llansadwrn (Anglesey) Weather

Last Month's Diary

July

1st: A sunny morning with a fresh to strong S'ly wind. Pressure 1009 mb was falling with low 987 mb off NW Scotland. A cold front lay over the Irish Sea to the west, but the morning was sunny and warm. The temperature at 09 GMT 19.2C had already exceeding yesterday's temperature and by 11 GMT had reached 21.8C and went on to 22.5C. During the afternoon the sky turned cloudier with the approach of the cold frontal from the west. The wind moderated and there was slight rain from 1700 GMT and moderate rain 1800-2000 GMT. [Rain 1.1 mm; Max 22.5C; Min 12.9C; Grass 11.3C]
2nd: A fine and sunny morning to at first. At 09 GMT pressure was 1006 mb but the sky was already beginning to cloud over and within the hour it was overcast. The S'ly wind was force 4/5 and visibility good, but hazy. The afternoon began cloudy, with a few spots of rain around 1330 GMT and a light shower at 1530 GMT, before becoming less windy with some sunny spells developing. There were storms in the south and in mid Wales, but they did not reach here. There was a heavy shower just before midnight. [Rain 0.9 mm; Max 17.4C; Min 12.0C; Grass 10.2C]
3rd: There had been a slight shower of rain at 06 GMT and at 09 GMT the sky was mostly covered with cumulus and altocumulus clouds. Pressure was 1006 mb in a surface low over the Irish Sea and convective clouds (see satellite image left) continued to darken. At 1100 GMT there was a thunderstorm, there were several bursts of thunder and lightning and a few minutes of heavy rain and lighter rain lasting 15 minutes overall with 9.0 mm rainfall accumulating. Later there were a few sunny spells and spots of rain before the sky began to clear during the evening. [Rain 9.0 mm; Max 18.3C; Min 11.5C; Grass 8.5C]
4th: A fine and sunny morning with 2 oktas cover of cumulus clouds, confined to the S over the mountains, cirrus and altocumulus. Pressure 1015 mb was rising in a ridge from high-pressure 1018 mb over NE France. Low 997 mb was to the SW over the Bay of Biscay with associated fronts moving into SW England. Here it was a mostly sunny morning, cloudier at times especially around noon, but similar in the afternoon. The light to moderate S'ly breeze backed E'ly by afternoon and strengthened during the evening with occasional light showers from 2200 GMT. [Rain 1.7 mm; Max 18.3C; Min 10.5C; Grass 8.8C]
5th: Rain showers continued at times through until morning. At 09 GMT with pressure steady on 1004 mb there had been a light shower in the past hour, but then it was sunny with cumulus in the vicinity. Visibility was good with a light to moderate veering S'ly breeze. Low 996 mb was off SW Ireland approaching St George's Channel and heading slowly our way. The NOAA 18 satellite image at 1339 GMT (right) shows the position of the low with its associated spiral of cloud with mostly cloud-free centre. Part of Ireland, Irish Sea, central and SE England and NW France are in a clear slot between the frontal cloud band. It was a day of frequent slight shower of rain and brief sunny spells, more like April than July! Winds were strongest and rain heaviest on the periphery of the depression, near the centre winds were light. The temperature rose to 19.5C; the most significant showers were at 1430 and 2100 GMT. [Rain 0.6 mm; Max 19.5C; Min 13.2C; Grass 10.8C]
6th: A fairly bright morning with showers in the vicinity and a slight one at 09 GMT. Pressure had fallen to 996 mb, lowest of the month, as the low 995 mb was over the Irish Sea off Holyhead. The wind was S'ly force 2 and visibility good with cloud around the mountaintops. Although it was a mostly cloudy day here there were bright and sunny spells most of the rain again falling on the periphery of the depression - up to 100 mm on the moors of Dartmoor were reported. It was sunnier, as frequently happens, in the north-west corner of the island where RAF Valley recorded 10.4 h of sunshine, highest in Britain. There was a slight shower around 17 GMT. [Rain 1.0 mm; Max C; Min 10.8C; Grass 7.8C]
7th: There was just over 0.5 h rain from about 08 GMT, at 09 GMT there was a break in the stratocumulus cloud over the weather station, but it soon closed over again. Pressure was 996 mb with the low 993 mb moved a little to the NE and over the North Sea. The morning was dull and damp, with a light NNE'ly breeze and only moderate visibility with low cloud on the mountains. The afternoon had just a few sunny breaks, but there were some spots of fine rain at times. [Rain 0.7 mm; Max 16.6C; Min 11.4C; Grass 8.5C]
8th: A fine and bright morning with 6/8 cover of mainly cumulus and altocumulus clouds. Pressure 1006 mb was rising in a minor ridge extending from high 1021 mb Spain and SW France. Looking to the low 993 mb S of Greenland had frontal cloud W of Ireland. A disappointingly cloudy day (solar radiation 16.94 MJ m ^-2) with the temperature rising to 16.6C in the rather few sunny spells. It a dry day the grass drying in the moderate to fresh SW'ly breeze. The sky was overcast for a while around 17 GMT then partially cleared for the late evening. Grass has not needed mowing for 14 days; growth has been 3.0 g m ^-2, fairly slow for July affected by the still relatively dry soil (50.4% dry mass) and somewhat below average temperatures (mean 15.0C (-1.1) and [-0.6] ). [Rain 0.3 mm; Max 16.6C; Min 9.5C; Grass 6.4C]
9th: Overcast and still dry at 06 GMT, but there soon a light shower of rain. Keeping dry around 09 GMT the day turned duller with rain or drizzle at times. With a temperature reaching 17.4C and little (E) or no wind it was damp and muggy; suitable conditions for the development of potato blight. There was no further rain after a moderate shower at 2100 GMT. [Rain 3.9 mm; Max 17.4C; Min 11.1C; Grass 9.6C]
10th: Overcast and dry with a moderate to fresh SSW'ly breeze in a temperature of 14.5C (dewpoint 12.1C; 86% RH); vegetation and potatoes were drying off nicely. Pressure was 1001 mb with complex low-pressure over Britain. Frontal cloud, and embedded low 998 mb was over the Irish Sea to the NW, but visibility was good and some breaks appeared in the cloud by 10 GMT and by noon it was mostly sunshine. With some passing fair-weather cumulus clouds, the only well-developed ones were seen to the S of here, the afternoon was mostly sunny and the temperature rose to 19.3C. By evening the sky was overcast once again with the frontal cloud returning . {Hawarden 20.7C, Valley 7.8h} [Rain 4.9 mm; Max 19.3C; Min 12.9C; Grass 12.3C]
11th: Overcast with low stratus cloud, very poor visibility in mist and rain. Pressure was rising slowly with the low 995 mb moving NE to be off Aberdeen, but we were under the slow-moving occluded front. The morning had intermittent rain or drizzle that began to ease by 1300 GMT. During the afternoon the cloud lifted and visibility improved to good; the sky remained overcast but some brightness appeared by early evening with further thinning. The day's maximum of 13.5C was lowest of the month. The night was mostly cloudy. [Rain 3.5 mm; Max 13.5C; Min 12.1C; Grass 12.0C]
12th: Some early morning brightness and a glimpse of sunshine before a light shower of rain at 0745 GMT. Pressure 1011 mb was rising with a minor ridge moving in from the west. The morning was mostly overcast, but dry. There was a light shower of rain around 1230 GMT and a few spots and drizzle early in the afternoon before once again turning dry. There were some glimpses of sunshine before evening that was mostly cloudy. {Milford Haven 17.0C, Valley 4.7h}[Rain 0.3 mm; Max 16.5C; Min 9.6C; Grass 8.3C]
13th: Dull at first, but becoming brighter with some sunshine by 09 GMT. Pressure 1015 mb was still rising in the ridge now centrally placed over Britain. The morning was partly cloudy with sunny spells and a light S'ly breeze and very good visibility. The afternoon was sunnier, the line of clouds over E Anglesey persisting while the W was clear. Despite this it was the bright day with solar radiation reaching 24.73 MJ m ^-2. Cloud, associated with fronts to the W, encroached by 18 GMT dulling the evening. {Great Malvern 21.4C, Hawarden 19.7C}. {Hawarden 19.7C, Aberporth 12.1h} [Rain trace; Max 20.7C; Min 10.2C; Grass 7.1C]
14th: A dull and damp start to the day with low uniform grey stratus and visibility < 2 km. It was misty at first with specks of drizzle on the moderate S'ly wind. Pressure 1020 mb was rising and the remnant frontal cloud began to lift and break before noon giving a little sunshine in a temperature of 18.7C. The afternoon was mostly cloudy, but the temperature reached 20.1C. {Rhyl 22.8C, Valley 1.2h} [Rain 0.0 mm; Max 20.1C; Min 12.9C; Grass 11.5C]
15th: Pressure 1024 mb had risen with Azores-high 1034 mb and Biscay 1030 mb. Deep low 994 mb was crossing eastward N of Scotland so we were under the influence of a warm and moist W'ly airstream. It had been a warn night, minimum 15.1C, exceeding anything in July 2007, but well below the 18.9C minimum of July 2003. The morning was dry, overcast and rather dull here with a strengthening WSW'ly wind; there was some clear sky over the Irish Sea to the NW and this part of the island had clear sunshine (see satellite image right). The afternoon here and in Snowdonia was partly cloudy with few sunny spells and the temperature rose to 22.5C, the evening was mostly sunny with the wind moderating. {Hawarden 23.5C} [Valley 9.9h] [Rain 0.0 mm; Max 22.5C; Min 15.2C; Grass 14.4C]

The first 15 days had a mean temperature of 15.1C (-1.0) and [-0.5] of the averages for the month. The mean minimum 11.7C was on the 30-y average, but (-1.2) of the past 10-years. The mean maximum 18.5C was (-0.8) and [-1.0] while the highest maximum so far 22.5C was (-3.0). Rainfall was 27.9 mm 44% of the average for the month.

16th: Overcast with stratocumulus clouds and a light to moderate W'ly breeze. Pressure was little changed on 1024 mb with high 1039 mb N Azores and low 994 mb Norwegian Sea we were still in the W'ly airstream. A succession of fronts were strung out across the Atlantic all seemingly headed under the jetstream established over southern Britain (see chart left). The morning kept dull with a few spots of rain in the vicinity. The afternoon was little better, after a few brighter spells the frontal cloud encroaching from the west thickened and there was light rain later. [Rain 10.5 mm; Max 17.8C; Min 11.2C; Grass 8.0C]
17th: Under uniformly grey low stratus cloud it was a dull sunless day with light rain or drizzle at times. Visibility was moderate to poor and SW'ly winds generally light. There was only a 1.4C variation in temperature over the 24-h 09-09 GMT. Solar radiation was only 5.85 MJ m ^-2 , lowest of the month. [Rain 4.5 mm; Max 14.2C; Min 11.5C; Grass 11.2C]
18th: More of the same; moderate drizzle interspersed with light rain making visibility very poor (1 km). Pressure 1009 mb was falling with Azores-high 1034 mb well to the SW and low 994 mb Norwegian Sea continuing the moist W'ly airflow with little change in prospect. There was more drizzle and occasional light rain through the day. Another sunless day with solar radiation of 6.20 MJ m ^-2. [Rain 2.4 mm; Max 15.6C; Min 12.8 C; Grass 12.7C]
19th: Overcast sky at first with the occasional bright spell and glimpse of sunshine. At 09 GMT it was overcast with a light shower of rain in progress. Pressure was 1006 mb with low 994 mb S Norwegian Sea and ridge of high-pressure from the Azores-high to the W of Ireland. Hurricane Bertha was on the 06 GMT analysis chart positioned SW of Nova Scotia west of the high-pressure; according to the GFS Model remnants eventually heading for Iceland. The morning had a few bright and sunny spells with the cloud lifting and breaking up. The afternoon was similar cloudy at times, but it kept dry. The evening was clearer for a while only to turn cloudier again by 2100 GMT. [Rain trace; Max 17.5C; Min C; Grass C]
20th: After a cool night there was dew on the grass with the grass minimum recording a minimum of 5.4C; in the screen the air minimum fell to 7.8C, lowest of the month. Pressure had risen to 1020 mb under the influence of the Azores-high expanding northwards. Again a day of infrequent sunshine, cumulus clouds giving a few spots of rain before noon, and with a cool N'ly breeze off the Irish Sea the temperature rose to 16.6C. The afternoon had variable but reducing cloud cover towards evening that was mostly sunny. It was mostly cloud covered by 2100 GMT, but there were sufficient clear spells at night to give bright moonlight. [Rain 0.0 mm; Max 16.6C; Min 7.8C; Grass 5.4C]
21st: Another cool night for the time of year, again much dew on the grass with a minimum of 5.2C, lowest of the month. Pressure was 1027 mb, highest of the month. A fine sunny morning with very good visibility under a few cumulus and cirrus clouds. The afternoon was less cloudy before turning cloudier by 17 GMT as a narrow band of rain approach the north-west and the Isle of Man, but it kept dry and mostly sunny here. Solar radiation reached 25.97 MJ m ^-2 , highest of the month. [Rain 0.0 mm; Max 20.4C; Min 8.0C; Grass 5.2C]
22nd: An overcast morning with some drizzle reported along the western coast of the island. Pressure was 1026 mb with high 1029 mb off the Scilly Isles with a band of frontal cloud lying to the N of here. The cloud began to burn away during the morning; the afternoon and evening were mostly sunny and warm in light S'ly breezes with the temperature rising to 21.1C. [Rain trace; Max 21.1C; Min 13.5C; Grass 12.1C]
23rd: Another overcast morning at first, but with holes appearing in the cloud here it was sunny and warm by the 11 GMT. Sea fog in Red Wharf Bay affected the Benllech area that remained cold until the afternoon, but here the temperature rose to 23.3C. [Rain 0.0 mm; Max 23.3C; Min 13.4C; Grass 10.3C]
24th: A bright morning with a 6 okta cover of cirrus and cirrostratus clouds. The wind was E or SE'ly and some high lee cirrocumulus undulatus clouds formed overhead. Pressure was 1018 mb with the high 1030 mb over S Norway and Sweden. Frontal cloud lay well to the W and there was a low-pressure centre developing W of Brest. The temperature at 09 GMT had risen to 21.2C (dewpoint 15.0C, RH 68%). The day was mostly sunny and warm with the temperature rising to 26.0C during the afternoon, highest of the month. The evening was overcast as thicker cloud cloud encroached from the west. [Rain trace; Max 26.0C; Min 14.7C; Grass 13.8C]
25th: Overcast with a few spots of rain just before 09 GMT. Overnight the air minimum did not fall below 17.6C, highest of the month. Pressure was 1010 mb with low 992 mb W of Ireland and high 1029 mb over Scandinavia. Frontal cloud was lying to the W with a shower trough with 2 narrow bands of rain gave a few spots of dusty rain here. Soon, the cloud was beginning to break and there was a little sunshine. Another warm morning with the temperature 20.7C (dewpoint 11.6C) rising to 24.3C during the day. [Rain trace; Max 24.3C; Min 17.6C; Grass 14.5C]
26th: A mostly cloudy day here with occasional spells of warm sunshine. The temperature at 09 GMT was 17.4C, dewpoint 15.7C and RH 90%. Lowest relative humidity during the day was 72% so it felt rather sticky as the temperature rose to 22.4C. The cloud dispersed towards evening that was the sunniest part of the day. Visibility had been generally moderate to poor with haze that lessened by nightfall, The night was calm and mostly clear. [Rain 0.0 mm; Max 22.4C; Min 13.2C; Grass 9.9C]
27th: The sky most clear early and 3 oktas at 09 GMT. The grass minimum was 8.2C and there was dew on the grass. During the morning the sky, once again, became cloudier. The afternoon was mostly cloudy with a light NE'ly breeze keeping a narrow ban of cloud across eastern Anglesey and to the mountains. It was clear on the west coast with RAF Valley reporting 14.2h of bright sunshine, the most in the UK. Later the cloud cleared away giving a mostly sunny evening. {London 30.9C, Tain Range 16.2 mm, Valley 14.2h} [Rain 0.0 mm; Max 20.2C; Min 11.1C; Grass 8.2C]
28th: A mostly cloudy morning, but there were brighter spells and glimpses of sunshine with a few holes developing in the stratocumulus clouds. It was warm, the temperature 19.5C at 09 GMT with a light NE'ly breeze. Pressure was 1016 mb with low 1007 mb heading N bring a band of thundery rain into SW Ireland, this stretching to just off the Scilly islands. Here it was a warm bright morning with the temperature rising to 22.3C by 11 GMT and reaching 24.4C in the afternoon. Keeping dry here and in the extreme west at Aberffraw several showers under dark clouds passed across the western/central part of the island affecting Bethel, Bodorgan and Valley in the afternoon. Overcast during the evening with flying ants emerging; last year they were seen here on 23 August Thunderstorms, moving N in England and the Welsh borders, brought thunder and 2 h heavy rain (10 mm) here from 2100 GMT. {London 30.2C, Trawscoed 27.8C, St Athan 19.2 mm, Aberporth 10.3h} [Rain 17.6 mm; Max 24.4C; Min 14.2C; Grass 11.6C]

At Tywyn Aberffraw 2 members of the gentian family were in flower, the red seaside centuary (Centaurium littorale, above right) and an early autumn gentian, the felwort (Gentianella amarella, above left). In places the dunes were carpeted with pink wild thyme and sometimes interspersed with white eyebright . There were plenty of butterflies around including gatekeepers .

The month ended with a rainfall total of 81.5 mm (131%) and [128%] of average. Rainfall in the year so far 679.5 mm, largest since the 720.8 mm in 1958, ranks 2nd since before 1929. The mean temperature was 15.9C (-0.2) and [+0.3] highest since 2004 (17.0C) ranking 9th highest since before 1979. There were 20 days that reached 20C, or more. Sunshine duration in Llansadwrn estimated from global solar radiation values was 183h, most since 2006 with 4 sunless days.