Temperatures will reach 30C in some parts of the country on Sunday - but other regions will be battered by thunderstorms.
The topsy-turvy weather will split the country as, while beaches across the south are expected to be extremely busy again in the heat, families in parts of the Northeast of England and Eastern Scotland are braced for potential flooding.
And a heat health warning from the UK Health Security Agency and the Met Office covers most of England, even the areas where storms are anticipated, and so people are advised to look out for the most vulnerable, such as the elderly.
It'll be most humid in Eastern England and the Southeast of England and temperatures in these regions will likely remain in the 30s for most of the day, forecasters warn.
Darren Bett, BBC forecaster, said: "The heat and humidity will all be pushed down towards eastern parts of England - 32C is possible in London and also Essex. It'll be quite uncomfortable here.
"But gradually western areas do turn cooler and fresher following the band of rain."
BBC weather maps indicate parts of Lincolnshire, Norfolk and Suffolk will also experience a 31C roasting on Sunday. It may mean tomorrow becomes the hottest day of 2023 so far, beating the 32.2C recorded in Surrey on June 10.
Yet Lincolnshire is also subject to the weather warning for storms, which will also bring heavy rain and gusts.
It also covers the rest of the East Midlands, all of North East England, swathes of Yorkshire and Humberside, most of Central, Tayside & Fife, parts of Grampian, Highland and the Scottish Borders.
"Some locations could see 30-40 mm in one to two hours," Met Office website states.
"Frequent lightning, large hail (up to three cm in diameter) and strong, gusty winds will be additional hazards.
"Spray and sudden flooding could lead to difficult driving conditions and some road closure.
"There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost."
The weather warning remains in place from 1pm until 9pm tomorrow.
The heat health warning from the UK Health Security Agency and the Met Office covers most of England, and is in place until Monday at 9am.
The warning, which urges people to "watch out for those who might struggle to keep cool in the hot weather", was issued as temperatures were expected to soar to 32C.
The warning covers London, the South East, South West, East Midlands, West Midlands, east of England, Yorkshire and Humberside.
