Category: Commentary

The north easterly wind comes from a cool quarter and the maximum temperature on Thursday reflected that in a peak of 20.4C. This was 5C to 7C down on previous highs the week but still 1.7C above the 36-year average.

The wind was quite brisk with a maximum gust of 22mph making this the windiest day the month September.

Under predominantly clear skies the thermometer fell steadily downwards to reach a minimum of 9.2C at 07.33 o Friday. The was exactly average for September.

Friday saw the sun shining as it rose above the horizon. A depression centred in the Bay of Biscay is tightening the isobars producing an increasing pressure gradient between it and the anticyclone centred over the North Sea. The wind is still from the north east but due to veer more into eastnoreast as the day progresses.

The centre of the high pressure on Wednesday was over Scandinavia that meant a significant change in direction and air mass from northwest to northeast and the windiest day of the month with a peak gust of 20mph. The cooler air mass meant a slightly lower maximum of 25.6C that was still 7C above the average.

We have now had thirteen consecutive days without rainfall. This is the driest period since early May when there were seventeen consecutive dry days.

The minimum overnight was also above average (+2.4C) with a low of 11.6C.

The brisk wind on Thursday is from the eastnoreast as the anticyclone that has given the recent dry sunny weather is now centred over Denmark. The sun was very red as it rose above the horizon at dawn due to thin high cloud brought by the easterly breeze but by 08.05 the sun began to shine strongly having triggered the sunshine recorder. The barometric pressure at 08.00 was 1028.7mb, the highest pressure since 28th May.

On Tuesday the sunshine, although reduced to 6.6 hours as cloud built up late afternoon, pushed the thermometer to a maximum of 26.4C. This was a 1C down on the Sunday peak but still 8C above the average.

We have now enjoyed a run of 12 consecutive dry days, which is the longest dry spell since early May when 19 consecutive rainless days were recorded. The rainfall for September still stands at just 3mm but the loss of equivalent rainfall through evaporation from ground sources and plant life has now reached 30mm.

The past night has again been mild with a minimum of 13.5C being 4.3C above average.

Wednesday arrived with misty conditions as the sun was initially hidden behind a cloud bank on the eastern horizon but at 08.15 the sun broke through in strength. The breeze on Tuesday came from a north westerly direction but as the centre of high pressure relocates to the north the wind on Wednesday is coming predominantly from the north east.

With the light wind and hot air mass originating in North Africa on Monday, it was not surprising to see the thermometer steadily climb to a maximum of 27.1C. This was not quite a September record for this station set up in 1984 as in September 2005 the peak was 0.1C higher and on 5th September 2004 the maximum was 0.2C higher. This peak was 8.4C above the 36-year average.

The air from a southerly direction always contains an element of pollution as it passes over the Continent but from North Africa it picks up very fine dust. Although there was almost no cloud on Monday the sky was light blue, not clear dark blue, and the UV only reached 3.9, being classed as ‘Moderate’. I also noted that the peak output from my solar panels was down about 0.5Kwh as compared to the output when the air came from the west or northwest earlier in the month when the cleaner air would have arrived after travelling over the sea.

Tuesday arrived with sunshine as soon as the sun got up that lifted the minimum of 11.4 C, being 2.2C above average, to 12.8C at 08.00.

On Sunday the 10.8 hours of sunshine and light winds from the south south west meant the thermometer rose to 24.3C. This was 5.6C above average and the warmest day since 18th August. With the sun now losing some of its strength the UV level at its peak is only in the ‘Moderate’ range.

It was another dry day, the tenth consecutive dry day this month. Rainfall for September is still just 3.0mm whilst evaporation amounts to 21mm.

The past night was cool with the thermometer sinking to 6.9C at 05.29 on Monday, which was 2.3C below average and the second coolest night this month after the 2nd (5.7C).

Monday dawned with thick fog limiting visibility to 200m. The sun, as a red globe, cold be seen shortly afterwards through the fog but it wasn’t until after 08.00, as the sun gained strength, that the fog began to thin improving visibility. By 08.30 the fog had totally dissipated.

The centre of the anticyclone is now much further to the east, close to Switzerland, also having intensified a few mb. This shift in position will mean the air mass will be brought from a more southerly or south easterly direction today.

Update on Monday at 16.10: temperature rose even higher than on Sunday with a maximum of 27.1C at 15.59. This was 8.4C above the average making it the hottest day since 12th August (34.1C)