A temperature of 26.5C (79.7F) was recorded in Kew Gardens, south west London, making it the hottest day of 2026 so far, the Met Office said.
Wednesday’s temperature beat 24.8C (76.64F) recorded in Mona on the island of Anglesey in Wales on Tuesday, which was also the “warmest 7 April on record”.
It was also hotter than temperatures recorded in some popular holiday destinations, including Ibiza and Rome.
The current warm spell is “well above” the early April average of 12C to 15C (53.6F-59F), forecasters said.
The warmth is due to southerly winds, but it will turn much cooler on Thursday as a more westerly wind develops behind a cold front.
Forecasters have also been warning people to be aware of high UV and pollen levels.
In a social media post, the Met Office said: “It’s the peak of the tree pollen season and levels of ash and birch pollen will remain very high across parts of England and Wales through the rest of the week.”
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Many people have also been enjoying the weather for the school Easter holidays by heading to the coast.
Sky News weather producer Jo Robinson said: “This is likely to be the warmest early April spell since 2020.
“UV levels will be moderate – which may catch people out after the long winter, while the pollen count will be very high for most.
“On Thursday, temperatures will be much lower just about everywhere, but southeast England will hold onto the warmth with temperatures into the low twenties.”
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The Met Office said daytime temperatures could fall by around 10C between Wednesday and Thursday ahead of “more unsettled” conditions later in the week.
Despite the warm sunshine across many parts of England, there have been cooler conditions in Northern Ireland and northwest Scotland.
The Met Office said there could also be outbreaks of rain.
