Category: Commentary

The heatwave intensified on Tuesday that saw the thermometer rise to a maximum 36.7C, which was a significant 14.0C above the 38-year average and broke the record set the day before for the hottest day at this site since set up in 1984. My station is on the edge of town so the peak in the centre of Marlborough would probably be at least 2C above my maximum. The modest breeze, with a peak gust of 18mph, continued from the southeast.

It was technically a heatwave as we have had at least three consecutive days with the maximum equal to or above 27.0C. In fact we have now had four consecutive days above 27C.

The dry weather continues, now 17 copious dry days, just 4.3mm on the 2nd.

The thermometer only dropped to 17.2C overnight being 5.3C above the average.

Wednesday began to with a predominantly cloudy sky that allowed only brief glimpses of sunshine. With minimal sunshine the thermometer only rose to 18.6C at 08.00, unlike Tuesday that registered 24.5C at that time.

The southerly air stream that brought the very hot air from North Africa and Spain, called a ‘Spanish Plume’, arrived with a vengeance on Monday. After a warm start the thermometer steadily rose, with a slight pause between 15.15 and about 15.30 due to variable cloud, to reach a maximum of 35.8C at 16.47. This peak was 13.1C above the 38-year average and broke the record for the hottest day I had recorded since this station opened in 1984, previously held with a peak of 34.8C on 19th jury 2006.

The air was very dry again with the humidity falling to just 28% at 16.10.

There was no let up overnight as the temperature did not drop below 17.9C, which was 6C above the average.

After strong sunshine at the start of Tuesday thin, light cloud began to slightly mute the strength of the the sun.

Set against the miserly rainfall of 4.3mm on the only day that rain fell this month, we are now losing the equivalent rainfall of over 5mm daily through evaporation from ground sources and plant life. The total loss through evaporation, due to the lack of rain, intense heat and brisk drying winds, now stands at 66mm for July so far.

Because of the lack of rain and high evaporation the humidity has been very low for the past few days. At this time of year the humidity at 08.00 is often from 80% to 90+%. Yesterday at 08.00 the humidity was 59% and lower again this morning at 08.00 read 56%.

Tuesday Monday
Temperature at 08.00: 24.5C. 22.2C
09.00: 29.1C. 25.6C
10.00: 32.8C. 29.9C
11.00: 33.6C. 31.7C
12.00: 34.2C. 32.2C
13.00: 35.2C. 34.2C
14.00: 36.3C. 34.1C. The current 36.3C exceeded yesterday’s record high
14.20: 36.7C. a new record!
15.00: 35.3C. 34.6C
16.00: 34.3C. 34.2C – cloud began to encroach after 14.40
17.00: 30.7C. 35.6C – weather front passing over – no rain

The thermometer soared to 29.5C on Monday being the warmest day for a week and 4.8C above the 38-year average. The light southerly breeze brought the first evidence of a ‘Spanish Plume’ with hot air from the Spain and Portugal. Overnight was again cool, thankfully, with a minimum of 10.9C, which was 1.0C below the average and 0.2C lower than the previous night.

Tuesday bought strong sunshine shortly after dawn that saw the thermometer rise very quickly to reach 22.0C at 08.00. This was the warmest start to a day since 20th July 2021 (22.9C).

Under the relentless sunshine, hot air and minimal rainfall, the ground is very dry thus the very low humidity reading at 08.00 of just 59%, the lowest humidity since July 15th 2013 (54%).

The barometric pressure has dropped 5.4mb since Monday as the high pressure relocates to eastern Europe and the low pressure system over Portugal begins to make itself felt carrying the hot air from far south.

Update at 10.00: current temperature of 29.9C.
11.00: temperature of 31.8C
12.00: temperature of 32.6C
13.00: temperature of 34.2C
14.00: temperature of 34.2C
15.00: temperature of 34.6C
16.00: temperature of 34.3C
16.30: temperature of 35.2C
16.47: peak temperature of 35.8C – surpasses previous record of 34.8C set on 19th July 2006.

N.B. My accurate weather instruments are situated up the garden some distance from hard standing and buildings.Importantly, they are well ventilated and completely shielded from sunshine and solar energy. The site is on the outskirts of Marlborough so the peak temperature in town could well be a degree or more above that recorded on my instruments. The station was established in 1984.

The thermometer climbed to 28.7C on Saturday making it the hottest day since Tuesday and 6.0C above the average. The UV level of 7.2 was again rated at Very High.

The past night has been the warmest for three night but still just below the average with a low of 11.1C.

The equivalent loss of rainfall through evaporation from the groud and plant life is running at over 4mm a day with 56mm lost this month set against the only wet day when 4.3mm was recorded.

Sunday arrived with cloud in the east that stopped the sun shining strongly until 06.00 when thin high cloud muted the strength until around 07.30 As the sun climbed higher the temperature began to rise rapidly so that by 08.00 it read 19.5C

The centre 0f the anticyclone has eased away eastwards, currently over Holland. This allowed the breeze to change direction on Saturday late afternoon from north to west and then south. Today it will have a more south-easterly component and beginning to bring in the very hot air from North Africa and Continent, having dropped out since 23.00 on Saturday until 08.30 on Sunday when there was a little movement.

Friday saw the thermometer edge a little higher with a maximum of 24.2C being 1.5C above the 38-year average.

It was the thirteenth consecutive dry day with the UV level at Very High. The breeze was light and predominantly from the north with a peak gust of 11mph but calm overnight.

It was another very cool night with a minimum of 7.4C, which was 4.5C below the average.

Saturday began with strong sunshine that lifted the temperature to 16.7C at 08.00. At that time the barometric pressure read 1025.8mb, almost exactly the same as Friday due to the anticyclone centred over the UK and only slowly edging eastward.