Forecasters said Tuesday would remain dry and bright across the country with highs of 26C or 27C.
But the Met Office warned of heavy downpours and a drop off up to 10C in temperatures on Wednesday.
The August Bank Holiday Monday became the hottest on record, peaking at 28.2C in Lincolnshire. The UK enjoyed a spell of fine weather with searing heat and cloudless skies over the weekend.
Met Office spokesman Oli Claydon told the Standard: “Today we are clinging onto the last of the warm weather with highs of 26C or 27C in London.
“This is the final piece of warm weather really. Tomorrow we could see as much as a 10 degree drop in temperatures as a cold front pushes through.
Torrential rain in London, August 9 2017
“We could see a few showers later into this evening and overnight. It’s going to have a much fresher feel with temperatures reaching 17C or 18C tomorrow.
“There’s a chance of rain as we go through the day. In the early hours, we could see some thundery, heavy downpours.
“A band of rain will be pushing eastwards across the south of the UK bringing more rainfall from lunchtime.”
Mr Claydon said the UK could expect brighter weather on Thursday with temperatures reaching about 20C in London.
Temperatures in the north of England will reach between 15C and 18C with the prospect of some pockets of frost before the end of the week.
