Windrush Weather

Yet another dull, cloudy and overcast day on Tuesday. The maximum temperatures over the last four days have been slowly descending with 12.8C, 11.6C, 10.4C respectively with 10.1C on Tuesday, which was 0.2C below my 40-year average. It was a dry during daylight hours but thick cloud and drizzle decided in the evening producing 0.3mm of precipitation. There was even less air movement, a maximum of just 7mph was logged on one rare occasion. but the anemometer was stationary for long periods.

The diurnal temperature range was just 0.4C overnight with a minimum of 9.7C just after midnight.

The start to Wednesday was as on previous days with low, thick cloud producing light drizzle in the air.

The jet steam has been positioned to the north of the UK keeping the cooler air to the north away and maintaining the high pressure, the projection is that this will continue for a few more days.

The high pressure has been intensifying having risen 7mb since Tuesday with a pressure reading of 1030.6mb at 08.00.

Monday was just like the three previous days under the thick blanket of cloud. The only minor variation was the temperatures, which were down a degree on each of the previous two days. The maximum of 10.4C logged at 13.17 was only just above my 40-year average at +0.1C and the coolest day since 13th September (9.8C). Once again, thanks to the duvet of cloud overnight the temperatures dropped just 2.1C with a minimum of 8.3C at 06.34 early Tuesday, which was 4.3C above the long-term average. There was barely any movement off air, a maximum movement on one occasion took the anemometer to just 8mph before falling light then still again.

Tuesday at first light revealed foggy conditions, initially limiting visibility to 600mm but just before 08.00 it was observed to have thickened dropping down to around 500mm visibility. This was due to low cloud masking the Marlborough Downs and Savernake Forest rather than fog formed by radiation when temperatures drop significantly overnight. The wind direction will be variable, probably between southeast, that the BBC forecast, and southwest that is in the Met Office forecast, if it can be measured under the lack of air movement.

The high pressure now extends from Ireland to well into Russia and down over the Mediterranean. It is blocking any weather fronts from advancing from the Atlantic and is likely to do so for a few more days. As a result more dull and cloudy days are ahead if relatively mild. The presser is slowly falling away with a reading at 08.00 of 1013mb, 1029mb, 1027mb and 1023mb respectively over the last four days.

The depressing monotony of successive cloudy, dreary days continued on Sunday. However, the continuous cloud cover meant anther mild day and night on Sunday. The maximum of 11.6C at midnight was 1.3C above my 40-year average whilst the minimum of 9.4C at 07.01 early on Monday was 5.4C above average.

The cloud was so dense on Sunday whilst the sun is weak, no UV light triggered the UV receptor, the first occasion since 23rd January 2024. Once again the diurnal range of temperatures, the difference between day and night extremes, was just 2.2C.

Monday revealed no change in our weather. We are still under the influence of the high pressure system acting as a dome trapping underneath it the relatively mild, moist air, with minimal air movement. What air movement there is will be from the east or southeast.

Saturday was a repeat of the gloomy, dull weather under the thick cloud trapped under the dome of the high pressure. However, it meant another mild day and night on Saturday with the thermometer peaking at 12.8C being 2.5C above my 40-year average and a minimum of 10.7C at 07.12 early Sunday, which was a significant 6.8C above average.

Sunday revealed a repeat of the previous two mornings with the persistent thick, low cloud masking any sunshine let alone any brightness.

The high pressure is still resident and likely to be for a few days yet so more of the calm, quiet, mild days. The wind will continue from an easterly direction.

Friday was a dull, dreary day with continuous cloud and no sunshine. However, the breeze from the west maintained the flow of warm, most air that raised the maximum temperature to 12.2C at 13.19 being 1.8C above my 40-year average. That thick duvet of cloud overnight meant a mild night with the thermometer not sinking below 10.3C at 06.45 early Saturday being a significant 6.3C above my 40-year average. The diurnal range of temperature was thus just 1.9C. It was a dry day.

Saturday revealed no change with a dull, dreary start to the day again under thick, low cloud. The pressure reading at 08.00 was 1031.1mb, the highest since 23rd October

The high pressure is drifting away to the east, currently its centre is heading towards Denmark and Germany. The dome of high pressure will continue to trap below it the moist air that is producing the thick cloud. A slight reposition means that any breeze will come from the east on Saturday but continue to be very light or calm for long periods.

October 2024 review

After a damp, dreary and very cool start to the new month an anticyclone developed to the north of Scotland that gave us two dry and sunny days on the 3rd and 4th.

The following week brought very wet conditions with considerable rainfall on the 6th to the 8th with 12.5mm, 10.6mm and a significant 23.9mm, respectively.

By the 9th there was a major change in the weather pattern as the wind veered int othe northwest and then north bringing a much cooler air stream that gave a maximum of just 11.7C on the 10th, which was the coolest day since 27th April. That was followed by a cold night that saw the thermometer drop to -0.4C producing not only a ground frost but the first air frost of the season.

A very wet and unsettled period arrived on the 12th with significant rainfall on several days. Three days brought us dull and dreary weather with continuous thick, low cloud and misty conditions, with little wind and fog on the 15th that limited visibility to 300 meters until late morning.

A large area of high pressure built and extended over the UK from the 22nd bringing dry and quiet weather with the breeze very light for several days. The peak barometric pressure occurred on the 23rd with a high of 1032.7mb, the highest since 17th September when the exact same peak was recorded. This anticyclone brought warm, moist air from Spain and the Bay of Biscay.

Another very large area of high pressure eased in from the Atlantic on the 29th bringing very calm, quiet weather. However, there was minimal sunshine because the air mass had travelled over extensive sea areas collecting moisture, which was trapped under the high-pressure dome. There were three days of minimal air movement with the maximum air movement of just 9mph.

The average temperature for the month was 0.3C above my 40-year average, principally due to slightly higher daytime peaks. It was the coolest October since 2020.

Once again, the monthly rainfall total was above my 40-year average with 101.6mm being + 10.6mm, however, it was the driest October since 2018. Only June and August in 2024 gave us below average rainfall totals. The rainfall total for the ten months of January to October stands at 972mm when the long-term average is 678mm.

Due to the numerus days with overcast skies, it was not surprising to find that the average UV level for the month of 1.9 was well below my fifteen-year average of 3.4. That means it was at the top end of ‘Low’ and not in the middle of the ‘Moderate’ category.