Temperatures in London are set to soar to 30C as the south basks in sunshine over the coming days.
Forecasters say the UK will see a split in weather across the country with the north facing torrents of rain while the south enjoys some end-of-summer sun.
The mercury will begin creeping up from Wedneday and is expected to peak on Tuesday with the mercury reaching a possible 30C.
But by the middle of next week, the whole country will see a return to unsettled conditions with temperatures dropping back down to normal September levels in the high-teens to low 20s.
Met Office spokesman Grahame Madge said that Thursday and Friday will see around 21-23C in London before increasing over the weekend.
He said: "The south east of England will warm up over the next week and into the early part of next week.
"On Tuesday, there is a possibility that we will see a three in front of the temperature.
"This is quite unusual for this time of year although it is not unprecedented. The record temperatures for September is around 35C."
Mr Madge said the south will see a few days of fine weather but there is a "real north-split divide".
He said there will be a "strong pattern for rain fall in the north" with heavy showers particularly in north west Scotland.
A yellow rain warning has now been issued in western Scotland from Saturday evening until midnight on Sunday.
Mr Madge said that by the middle of next week the weather is turning more unsettled and temperatures will drop back to normal levels for this time of year.
