The first half of this month was the hottest for nearly 175 years, forecasters have said.
Temperatures hit highs of 27.5C and the average of 15C was the highest since 1833.
But forecasters warned the weather is likely to stay cooler for around a week before picking up again by next weekend.
That means the hot weather should be arriving in time for the Bank Holiday.
The hottest place for the first 13 days of May was Great Malvern in Gloucestershire.
The hot weather was caused by an area of high pressure over the North Sea which "dragged in" hot air from the South East, forecaster Paul Mott from Meteogroup said.
"We are now seeing that high pressure moving away to the West, so we are going to get colder North East winds coming in.
"Over the next four or five days it will be quite a lot cooler, but it will warm up by next weekend."
Temperatures could return to the low 20s by the end of next week, but that change may also bring rain to western areas.
Brits flocked to the beaches over the May Day bank holiday. Resorts on the south coast reported record crowds for the time of year.