Month: September 2023

The arrival of thin cloud late afternoon on Thursday meant a maximum of 29.8C was just below the peak of Wednesday, even so it was 10.9C above the 39-year average. The residual warmth in the ground from the heat of the day and cloud cover meant another very warm night with a minimum of 15.C being 5.7C above average.

The last few days have been memorable for not only the heat but very calm conditions. Many days have seen air movement and a peak gust in single figures. For much of the past night the anemometers have been stationary. During these periods thin threads of gossamer have floated in the air and wrapped themselves around at least one anemometer. It took a very long fibre glass extending pole to reach the anemometer, three metres above ridge height, and free up that instrument as it takes a surprisingly strong gust for the instrument to break free.

Friday began with weak sunshine due to high, thin cloud. The air movement is forecast to veer into the southwest today, not seen since last month, and continue very light as the anticyclone begins to move away. The barometric pressure has dropped 10mb since its peak on Saturday.

Update at 17.15: thermometer rose above 30C again with a maximum of 30.2C at 15.38, fractionally down on the record high of 30.3C on Wednesday.

Technically Marlborough has now experienced a ‘heatwave’ as described by the Meteorological Office. We have now had three consecutive days when the maximum daily temperature exceeded 27C, the threshold set for Wiltshire. The peak on Wednesday was 30.3C being a significant 11.4C above the 39-year average. It was the hottest September day I have recorded since this station was set up in 1984 and the hottest day of the year.

It was also a very warm night as the thermometer did not drop below 16.9C, recorded at 05.23 on Thursday, being 7.6C above the long-term average.

The UV level is still peaking at High with the loss of equivalent rainfall through evaporation from ground sources and plantlife exceeding 3mm each day.

Thursday revealed a sun behind misty conditions, however, by 08.00 the thermometer had risen 19.5C. The barometric pressure continues higher reading o 1018.1mb at 08.00, thanks to an anticyclone centered over Scandinavia.

Update at 17.30: cloud encroaching late afternoon limited temperature rise to 29.8C. Maximum of 30.3C yesterday. Evidence of Saharan dust on car this morning.

The thermometer rose steadily on Tuesday to reach a maximum of 28.6C. This was a significant 9.7C above the 39-year average and the hottest day since 25th June (28.7C). The threshold for a heatwave for Wiltshire is a minimum of 27C for three consecutive days, therefore, if the thermometer rises to a peak of 27C or above today, it can be classed as a heatwave. Three neighbouring counties to the east of Wiltshire had their threshold lifted to 28C last year due to the continuing rise in global temperatures. The UV value of 5.2 was still in the High category.

The low of 13.4C was identical to Monday night being 4C above the average. This was far from a ‘tropical night’ that needs a minimum of 20C to be so described.

Wednesday dawned with misty conditions that meant the sun was initially weak. However, by 08.00 the thermometer read 15.7C. The barometric pressure continues high with a reading of 1019.7mb at 08.00. The hot, moist airstream continues to be brought from the Continent on a very light wind varying between northeast and southeast as the result of high pressure over Scandinavia and low-pressure over the Atlantic, the former rotating clockwise and the latter anticlockwise, feeding the air from the Continent.

Update: a maximum of 30.3C was recorded at 15.54, making it the hottest day this year. This was also a September record for my station set up in 1984. The previous high was 27.1C in 2020. I confirm that we are experiencing a meteorological’heatwave’ as we have endured three successive days with a maximum in excess of 27.C

After the fog cleared on Monday the sun began to lift the temperature rapidly to reach a maximum of 28.3C, which made it the hottest day since 25th June and a significant 9.6C above the 39-year average. The warmth lingered overnight that saw the thermometer not drop below 13.4C being 4.2C above the September average.

Tuesday briefly saw radiation fog in the River Og valley that dispersed very rapidly after the sun crossed the horizon. By 08.00 the thermometer had risen to 17.2C. The ridge of high pressure continues to feed very warm air from the continent on a gentle breeze varying between north northeast and southeast as the day progresses.

August 2023 Review

The regime of sunshine and showers continued during the first week of August with rain every day until …. thanks to Storm Patricia, named by the Météo France as the major impact was over their country

Storm Antoni arrived in the early hours of the 5th with more rain and rising wind strength, maximum gust of 28mph, that had backed from the northwest of previous days to south. The rain, mostly light, continued from 07.00 to 22.30 on the 8th

A short-lived ridge of high pressure from the 9th to the 11th, brought welcome relief from the previous consecutive wet days. At last, the thermometer rose above average with 24.9C on the 9th and 25.8C on the 10th. The latter was 3.2C above average and the warmest day since 7th July.

The night that followed was very warm and muggy with the thermometer not dropping below 17.12C, which was a significant 5.4C above the average and the warmest night since 3rd August 2022.

After yet more rain days from the 13th to the 14th, a temporary ridge of high pressure built. This resulted in not only very welcome dry days but the thermometer climbing above the average.

This was followed by two wet days before a ridge of high pressure from the south gave us several sunny days and the warmest day since 7th July when the thermometer peaked at 26.0C on the 23rd.

The dry period of six consecutive days from the 19th to the 24th was the longest dry period since the first week in June and was very welcome.

A cold front passed our way on the 25th that saw temperatures begin to fall away with the coldest night in the early hours of the 27th as the thermometer dropped away to 7.4C being 4.4C below the average.

The average temperature for the month was 0.2C above the average.

The rainfall of 73.0mm was 7.2mm above the average.

Summer 2023

The rainfall of 251mm was some 73.3mm above the 39-year average and the wettest summer since 2012, which was a record with 328mm.

The mean temperature was 0.6C above the 39-year average

Update: peak temperature of 28.6C at 15.44, up 0.3C on the Monday maximum. If tomorrow exceeds 27C, which is expected, will officially be classed as a heatwave. Also, will it be a ‘tropical’ night? More detail on Wednesday.

The many hours of strong sunshine on Sunday, after the fig lifted, pushed the thermometer to 25.7C. It was the warmest day since 11th August and 6.8C above the average.

A mild night followed with a minimum of 14.3C being 4C above the average.

Monday after dawn saw the fog thicken with a minimum visibility of 200m. Just after 07.30 the fog began to slowly thin.

Update: maximum of 28.3C at 15.45, which was highest since 25th June (28.7C)