Tuesday 21st July
Monday was similar to Sunday, and to what we might expect today, that is, many hours of strong sunshine that yesterday lifted the thermometer to a maximum of 25.8C at 16.44, which was 2.9C above my long-term July average. Also noted was the fact that temperatures are beginning to climb upwards again. Likewise, the overnight minima have started to rise with a low of 10.7C at 05.42 early Tuesday, after sunrise in Marlborough at 05.15.
Tuesday arrived with clear sunshine after sunrise that had lifted the temperature to 17.3C by 08.00, and still climbing steadily, that indicate another even warmer or hotter day today. The barometric pressure continues to build with a reading of 1029.3mb at 08.00, which is the highest pressure since the peak on the 3rd.
There’s little change over the next few days as the high pressure maintains its grip over the UK whilst slowly edging southwestwards. There are indications that by the weekend it will begin to lose the battle with areas of low pressure forming around Iceland that will attempt to push weak weather fronts down across the country. If the fronts produce any precipitation, the current thinking is that minimal rain, or none at all, will reach central or southern England.
There are indications that the coming weekend will see maximum temperatures fall to just above the July average before likely rising again into next week.
The Met Office have recently released an interesting paper on the effects of the marine heatwave in 2023, and of course which is also occurring this year.
Author: Met Office
06:00 (UTC+1) on Tue 21 Jul 2026
New joint research from the Met Office and the University of Reading has revealed that a prolonged marine heatwave in the North Sea played a significant role in intensifying the impacts of Storm Babet (18 to 21 October 2023).
The study, ‘Marine heatwave amplifies extreme multi-hazards of extratropical cyclone Babet’, published in the Natural Hazards and Earth System Sciences journal, finds that unusually warm sea temperatures increased rainfall, river flows, storm surge and wave energy during the storm, amplifying impacts by between 9% and 20%.
Findings demonstrate that marine heatwaves can impact weather on land. Waters around the UK are currently experiencing widespread marine heatwave conditions, which earlier in July reached up to Category 4, classified as “extreme”, a level rarely recorded in UK waters. This is linked with recurrent atmospheric heatwaves, bringing long-lasting sunny and calm conditions for the third time this year, giving sea surface temperatures little opportunity to cool.
The attached image is of the horse about to be attached to the barge on the Kennet and Avon Canal
Marine heatwave added energy to the atmosphere
The study provides the clearest evidence to date that marine heatwaves in the North Sea can act as amplifiers of UK storm hazards, driving increases in rainfall, river flows, storm surges and coastal wave energy.
Lasting almost seven weeks, from 1 September to 21 October 2023, the North Sea marine heatwave warmed the full depth of the shallow basin by around 0.8-1 °C. These unusually warm conditions resulted from persistent anticyclonic weather, allowing the ocean to absorb and retain excess heat.
Storm Babet induced a low-level wind jet, a fast-moving stream of air close to the ground that helps storms grow stronger. As the wind jet came from the east, bringing heavier rain than usual to many areas, the warmer than average waters:
• Increased evaporation and added extra moisture to the atmosphere, contributing to around 5% heavier rainfall over eastern Scotland during the storm
• Deepened the storm slightly, lowering central pressure by around 1-2 hPa compared to a cooler ocean scenario, indicating a modest but measurable intensification
• Enhanced atmospheric instability, strengthening the low-level jet