Wednesday's temperature beat the 24.8c (76.64f) recorded in mona on the island of anglesey in wales on tuesday, which was 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.
In a post on social media, the met office said: "for context, temperatures above 26c are very uncommon in early april.
"indeed, today has been the second warmest day on record during the first half of any april."
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.
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."