Author: Eric Gilbert

The very strong, relentless sunshine on Monday, combined with the UV level ‘Very High’ again, pushed the thermometer to 31.1C at 16.36. This peak was a significant 10.7C above my long-term average making it the hottest day since 14th August 2022 when 33.2C was logged.. The hot air persisted overnight that saw the thermometer not drop below 18.5C, logged at 05.17 early Tuesday, just after dawn in Marlborough at 04.54.

Tuesday began with variable cloud and some early sunshine, but cloud began encroaching from the northwest so by 07.00 it became muted. The considerable heat by day and night has resulted in a ground temperature at a depth of 5cm reading 25.2C at 08.00.

A cold weather front is edging down from the north, which is bringing the increased thin and variable cloud that heralds the change in our weather pattern.

We have recently been under the edge of a heat dome that was centred over Spain, Portugal and France that had been trapping hot, stagnant air beneath it. As the weak weather front eases southwards today, combined with a low pressure system in the North Sea, the wind will come from the west, bringing a fresher air stream as the day progresses, thus the peak temperature today will not quite reach the high of Monday as the recent heat is slowly being edged eastwards.

There is news today of the first ever geostationary satellite to provide 3D profiles for temperature and humidity for Europe being launched today. This will provide data to enhance the next generation of weather forecasts. It is the second satellite as part of a series of six which will revolutionise and safeguard weather forecasting across Europe for the next 20 years. The Met Office say ” This international collaboration is vital in ensuring that recent improvements to forecast accuracy can be safeguarded and enhanced in the coming years.”

Due to family commitments the June review will be one day late and appear tomorrow.

With little breeze from the west and relentless strong sunshine the thermometer slowly edged up all morning on Sunday hovering for a while at 27C at 15.24 before a sustained burst of sunshine and accumulated heat lifted the maximum to 27.4C at 16.24. The highest solar energy was logged at 12.55 with 1257W/m2 recorded, simultaneously, the UV peaked with a value of 8.5, the highest since 13th August 2024, which was at the top end of ‘Very High’. Initially the thermometer slowly edged downwards overnight, under clear skies, with a minimum of 13.6C logged in the very early hours at 03.09 on Monday, however the back track of the cloud radar showed thin, high cloud drifting in from the south just before 04.00. Early risers would have seen on Monday morning that the cloud limited the sunshine after dawn with misty conditions but by 07.30 the sun was beginning to find breaks and lifted the temperature to 19.9C by 08.00.

Monday will see the temperatures rise very high again, especially as the air stream backed from west yesterday to southeast overnight with this morning wafting hot air from the Azores region courtesy of the Azores High. The centre of the high has eased a little eastwards over the Netherlands hence the change in direction.

A small disturbance, minimal low pressure area, will form off the southeast coast of the UK tomorrow, so there is an outside chance of some light rain in the afternoon, with the wind briefly backing into a northerly quadrant.

With no rain possible today the total rainfall for June will stand at 37.1mm against my 41-year average of 52.9mm. Due to the heat and warm winds there has been an equivalent loss of rainfall, due to evaporation from ground sources and plant life, of 110.1mm.

The opposite to wind chill in the winter was again apparent on Sunday. Using data from the wind strength, temperature, humidity and also solar activity, outside at 14.00 it felt more like 30.9C when the thermometer registered 25.3C.

I am starting a new series of images for a week or two of bees that are so important to crops, taken from my library over the post 50 years. They were taken at various times in the year.

The sunshine was intense on Saturday pushing the thermometer mid-afternoon to a maximum of 28.7C being a significant 8.1C above average. Light variable cloud limited any further rise but this was the hottest day since the 21st when 29.7C was logged. The past night was slightly cooler than the previous but a minimum of 17.1C was still 6.9C above average.

The start to Sunday revealed a mainly cloudy sky although there were brief brighter intervals in the minimal cloud breaks before 08.30. The thermometer had risen to 20.0C by 08.00.

The anticyclone is now firmly in control of our weather until at least Wednesday although Monday will probably bring the peak temperature. The centre of the high pressure, current barometric pressure is 1026.5mb, lies over the English Channel that will see the continuation of a westerly breeze today, backing into a more southerly direction on Monday that will increase the heat, and then likely to change significantly into a northerly quadrant on Tuesday before temperatures fall away considerably on Wednesday. By Tuesday we will have had four consecutive days with the maximum above 27C.

The heatwave threshold for the Marlborough area is 27C. The maximum yesterday was above that figure, which will happen again today and also tomorrow. Thus we are technically experiencing a heatwave, which is described as three consecutive days with temperatures rising above the heatwave threshold. The original heatwave thresholds were based on the reference climate period of 1981-2010 and were intended to be flexible and revised in the light of climate change, therefore the heatwave thresholds were revised in 2022, using the most recent 1991-2020 climate averaging period, with the local threshold temperature rising from 26C to 27C. The review saw six counties move from 27C to 28C, one from 26C to 27C and one from 25C to 26C, the areas changed were in the south of the UK and the Midlands.

The nearby anticyclone really began to dominate our weather on Friday that brought heat and humidity and saw the temperature rise to a maximum of 26.8C being 6.2C above my long-term average. The UV level of 7.9 for the second consecutive day was well into the ‘Very High’ category. Cloud cover overnight persisted and looking at the track on radar it indicated that it began to thicken around 05.00, which is why the minimum of 18.4C was a significant 8.2C above average and made it the warmest night since 13th August 2020 when a low of 19.4C was logged.

The heat factor, using the data of temperature, wind speed, humidity and solar activity, calculated that outside it felt more like 31.5C when the thermometer read 26.6C.

Saturday revealed low, thick cloud and thus no sunshine to greet the new day. The anticyclone has continued to build and dominant our weather with the barometric pressure reading of 1023.7mb at 08.00, up 10mb since Wednesday.

The forecast is for the heat to continue to build and peak on Monday, with Tuesday down a few degrees and the rest of the week much closer to July temperatures. It is likely that we will technically be experiencing a heatwave over the next three consecutive days as maxima are likely to equal or exceed 27C, which is the heatwave threshold for Wiltshire.

The image taken in 2015 is from St Peters Church tower in Marlborough, looking south with Savernake Forest in the background.

The variable cloud on Thursday, especially in the afternoon, combined with the very brisk westerly breeze, muted the temperature a few degrees with a maximum of 22.3C logged at 13.15, being the lowest for three days but still 1.7C above average. A narrow band of rain arrived at 10.25 that produced just 1mm in a very sharp shower, but within an hour all evidence of the rain had disappeared as the sun returned. More rain was observed starting at 22.30, light at first and a little heavier just before midnight, that amounted to 2.0mm. Although it was a cloudy night the thermometer sank to its lowest for eight days bottoming out at 11.6C logged at 05.29, being 1.4C above average.

Friday began with strong sunshine that lifted the temperature to 17.5C by 08.00. However by 08.30 variable cloud began to obstruct the sunshine.

The rainfall total for June to date is 37.1mm compared with my 41-year average of 52.9mm. However, the equivalent loss of rainfall through evaporation from the ground and plant life this month is triple the rainfall total with 96.7mm of moisture lost due to the heat and brisk winds that occurred on many days.

There are a few days left in June but both the average maximum and average minimum are currently a significant 2C or higher above my long-term average. An Amber Heat Health Alert has been issued for today and the next four days, which is one step up from a Yellow warning.

The high pressure to the south has begun to assert itself as it gets closer and currently extends from mid-atlantic to the east of the Continent. The forecast track of the Jet Stream indicates that the very hot weather will build today and last until at least Tuesday. There are indications our area will be influenced by a heatwave that has been developing across western Europe.

The image was taken from St Peter’s Church tower in Marlborough in 2015 looking across part of Marlborough College.