The heatwave is set to continue well into next week in parts of Britain, following a weekend of record-breaking temperatures.
The mercury peaked at 30C in parts of the country on Saturday, making it not only the hottest day recorded in October but also the third hottest of 2011.
And the unseasonably warm weather will carry on until Tuesday in the South East, forecasters said, when the highest temperature will be a cooler 20C.
Gareth Harvey, forecaster at MeteoGroup, said: "It will be fairly miserable across northern Ireland Scotland today, with further spells of rain, but the fine weather should hold up in parts of England and Wales.
"It might be more unsettled across northern Wales and northern England, but for most of central, south-eastern and southern parts of England it should be another nice day.
"It might not be as warm as yesterday, but we'll see the odd 29C in one or two spots towards the South East.
"It cools down a bit on Monday, but temperatures will be still be well above average - around 25C in the South East and East Anglia."
The weather will be fresher on Tuesday, however, with highs of around 20C in the South East. "This is still above average, but not well above average," Mr Harvey said.
Similar temperatures are expected on Wednesday, but cooler air will set in on Thursday.
Mr Harvey said: "From Thursday onwards it will be very windy, with some cool air across the whole of the country and some heavy showers. Temperatures on Thursday will peak at 17C-18C in the South East. By Friday the highest temperature in the country will be about 15C-16C, which is half of what we saw (on Saturday)."