The United Kingdom’s latest heatwave reached an extraordinary peak on August 13 as Kew Gardens in London recorded a provisional temperature of 38.1°C (100.6°F).
The Met Office confirmed that the reading makes Thursday the hottest day of 2026 so far and the fifth-hottest day recorded in the UK.
The temperature also continues an unusual sequence of extreme summer heat affecting the country.
But reaching 38°C requires more than simply a sunny August afternoon.
Temperatures provisionally reached 38.1°C at Kew Gardens, making it the hottest day of the year so far
— Met Office (@metoffice) August 13, 2026
This is the second time this year we have reached 38°C. The only other time this has happened twice in one year was in 2022.
It also makes it the 5th hottest day on record pic.twitter.com/vYvkpXda32
Several atmospheric and surface conditions have aligned to push temperatures toward the upper edge of Britain’s historical climate.
Persistent high pressure has dominated the weather pattern. Within a strong anticyclone, air tends to sink through the atmosphere.
As that air descends into regions of greater atmospheric pressure, it is compressed and warms. Subsidence also discourages widespread cloud formation.
With fewer clouds blocking incoming sunlight, large amounts of solar energy reach the surface for hours at a time.
At the same time, very warm air has been transported toward Britain from continental Europe. The Met Office confirmed the 38.1°C reading while noting that rain is eventually expected to return to parts of southern Britain. Met Office heatwave update
🇬🇧 UK drought bakes London pond as new heatwave builds
— AFP News Agency (@AFP) August 13, 2026
Aerial images show the dried-out banks of a pond in London, as the UK's Met Office says a new heatwave is set to hit southern and central England. pic.twitter.com/zT1TZBXHM3
Britain’s dry ground is making things hotter
Soil moisture plays an important but easily overlooked role in extreme temperatures. When the ground contains plenty of water, some incoming solar energy is used for evaporation. That process consumes energy that would otherwise heat the surface. After prolonged dry weather, less water is available.
A greater proportion of the Sun’s energy can therefore go directly into sensible heating of the ground and lower atmosphere. This feedback can add extra intensity to an established heatwave. Large cities retain heat exceptionally efficiently. Concrete, brick and asphalt absorb energy during daylight and release it gradually after sunset. Urban areas also contain fewer vegetated surfaces capable of providing evaporative cooling. This produces the urban heat-island effect. The consequence is not merely hotter afternoons.
Nighttime temperatures can remain elevated, reducing the opportunity for buildings and people to cool before the next day’s heat arrives. That accumulated heat stress becomes increasingly important as an extreme spell continues.
This is perhaps UK’s last heatwave for this year
The heat will not persist indefinitely. As the dominant high-pressure pattern shifts, Atlantic influence is expected gradually to return.
That transition can itself create active weather.When cooler air encounters an exceptionally hot air mass, instability can increase and thunderstorms may develop.
For now, however, the August 13 measurement has secured another place in Britain’s weather records. A temperature of 38.1°C (100.6°F) remains extremely unusual for the UK, even after the growing number of major heat episodes recorded during recent summers.
