Tuesday 1st September
The last day of August was dry and fine with the thermometer reaching just above the average with a maximum of 22.3C at 14.30 before cloud increased, being 0.7C above my August average. The last night was cool that saw the thermometer fall away to a minimum of 7.7C at 05.18, which was an hour before sunrise in Marlborough at 06.19, being 4.1C below my long-term average.
Tuesday revealed much cloud that limited the sunshine after dawn, which meant the thermometer had only risen to 9.9C by 08.00.
The modest high pressure to the south will give us a fine day today and tend to hold off weather fronts pushing down from the north, associated with the depression near Scotland, for much of the week.
August 2026 review
The month began, where July finished, with the continuation of high temperatures. By the 2nd the peak temperature had risen back above the heatwave threshold for Wiltshire of 27C, and continued for three days, the fifth official heatwave this year in Marlborough.
Thankfully, from the 5th, peak temperatures dropped due to the breeze backing into the west arriving from a cooler Atlantic rather than the hot Continent. The 7th gave us the coolest night of the month, since the 14th June, with a minimum of 5.7C, under clear skies and calm conditions, also the coolest night since 16th May, the latter being a significant 6.1C below average.
The sixth brief heatwave for 2026 began on the 11th and was even more intense that saw temperatures rise well above 30C with a high of 35.9C on the 13th.
The significant change in our weather pattern arrived on the 17th. The high pressure had receded westwards allowing a depression to the northwest to edge closer. Its associated cloud meant less strong sunshine and weather fronts beginning to cross the country.
There were numerous showers drifting across the country on Thursday the 20th but as usual, they were averse to dropping any significant precipitation on Marlborough. There were a couple of times when for a minute a few drops dampened the ground mid-afternoon and early evening that amounted to 0.6mm. However, as soon as the sun reappeared the ground dried up rapidly.
On Friday the 21st at first light, there revealed that a bank of fog had formed in the early hours due to the recent moisture in the air condensing as the temperature dropped, that included thicker radiation fog in the River Og valley. By 06.15 the visibility across the River Og valley was restricted to about 400m whilst less dense towards Savernake Forest. By 06.30 the sun had begun to creep above the fog bank and visibility slowly improved.
From time to time over the last week or two of August I had seen headlines that suggested there could be another heatwave in September. I had seen nothing in the meteorological data that at that time indicated that temperatures might rise very high again. However, as a matter of interest I analysed my statistics when the heatwave threshold of 27C for Wiltshire had been equalled or exceeded over the past fifteen years. Taking three five-year spans, I found that from 2012-2015 there were 15 days, during the period 2016-2020 the heatwave conditions totalled 57 days and from 2021-2025 there were 76 heatwave days. A distinct upward trend in the occurrence of heatwave days was obvious. The year with the highest number of heatwave days was 2028 with 25, followed by 2025 with 21. So, how many this year so far – 38!
During the night of the 26th/27th a large area of thundery activity developed over Northen France and Brittany and headed across the Chanel towards the UK, arriving in the early hours. Thunder was heard at 05.25 and the rain gauge triggered from 05.18 to 06.00, producing a total of 5.0mm. I have often noticed, under shower conditions, not wide rain bands, that the approaching rain area thins and fragments as it approaches central England, this was the situation overnight as much heavier and persistent rain was observed on the radar to the west and east of Marlborough.
That night was very warm and humid with a minimum of 17.7C that made it the warmest night of the month and the rainfall, not surprisingly after such a dry period, produced very humid conditions with a reading of 94.2% at 08.00.
Headlines in the press this past month have highlighted the extreme temperature for the UK of 30C, and its frequency this year and over recent years. Once again, I have analysed my data over three five-year periods to examine the local situation. Between 2011 and 2015 there were just five days when 30C was reached or exceeded, from 2016-2020 there were 19 days and from 2021-2025 a total of 28 days, a clear rising trend over that period of 15 years. This year so far there have been 19 days when 30C was reached or exceeded. The peak this month was 35.9C on the 13th being a significant 14.3C above my long-term August average.
A couple of low-pressure systems decided to visit us over the Bank Holiday weekend. Although their arrival was not welcomed by holidaymakers, they were well received by gardeners as 18.4mm of precipitation was recorded during many hours of light rain, drizzle and occasional heavier bursts on the 29th that began to rejuvenate parched gardens. This was the wettest day since 1st June when 28.0mm was recorded.
The average temperature for August was 2.5C above my long-term average mainly due to the very hot days. An analysis indicates that the maximum was 4.2C above average whilst the minimum was 0.8C above average. It was 0.1C above the average for the very hot August of 2022 that also had heatwaves.
The total rainfall was 43.0mm, being 59% of my 43-year average. The rainfall for the eight months January to August was 460mm, compared to my 43-year record of 516mm for that period. Although it has been a very dry summer the months of January and February were well above average.
Summer 2026
The total rainfall for our very hot summer was 97mm compared to my 43-year record of 177mm, principally due to the very wet 1st June and the significant fall on the 29th August.
The average temperature was 3.2C above my long-term record.