Thursday 23rd July
The temperature crept higher again on Wednesday, just 0.2 above the Tuesday high, with a peak of 26.6C at 17.03 being 3.7C above average. The past night’s minimum was also very similar to the previous night, once again a difference of just 0.2C, with a low of 13.3C at 06.19 being 1.3C above my long-term July average.
The UV level rose back to High again on Wednesday whilst the peak solar radiation was also high with a reading of 1058W/m2 at 12.29, probably due to a slight variation in the wind coming more from the north that is likely to have been a clearer air stream having travelled a considerable distance over northern waters.
Thursday began very muted initially as cloud had drifted across that was noted on the back track of the radar arriving just after 00.30 that limited the strength of the sun after it had risen in Marlborough at 05.17. However, by 08.00 the thermometer had risen to 17.9C, which made it the warmest start to a new day at that time since last Friday.
The centre of our, what seems resident, anticyclone is still slowly drifting southwestwards but will not depart completely as it will throw a ridge of high pressure back northeast over mainly southern England. Over the next few days the depression over Iceland will deepen a little and begin to cast its cloud over Scotland and possibly northern England that by Sunday will have pushed even further south containing a weather front that just, might just, produce a little precipitation here during the early hours of Sunday morning.
N.B. The image of the horse drawn barge on the Kennet and Avon Canal does not depict an emergency. At this point the horse is uncoupled and the boat rotated 180 degrees ready for its return journey.
Marine heatwaves: why warm seas matter for UK weather
Author: Met Office
Tue, 21 Jul 2026
While the recent heatwave over land is fading, the heat has not disappeared entirely.
Around the UK, sea surface temperatures remain significantly above average, continuing a trend of marine heatwave conditions that has become increasingly notable in recent years.
These prolonged periods of unusually warm seas can influence marine ecosystems, coastal weather and even the severity of major weather events.
What is a marine heatwave?
Marine heatwaves are measured differently from heatwaves on land. Rather than relying on a fixed temperature threshold, they are defined relative to what is normal for a particular location and time of year. A marine heatwave occurs when sea surface temperatures remain above the 90th percentile of a 30-year climate record for at least five consecutive days.
Depending on how far temperatures exceed this threshold, events can be classified as strong, severe or extreme.
This approach reflects the fact that sea temperatures vary widely around the UK. A temperature that would be exceptionally warm in one area may be perfectly normal elsewhere.
A growing feature of UK waters
Recent years have seen an increasing number of marine heatwave events around the UK.
According to Met Office scientists, 2025 was particularly exceptional, with marine heatwave conditions persisting for more than three-quarters of the year. Similar events were also recorded in 2022 and 2023, while 2026 has once again seen sea temperatures significantly above average.