Temperatures will soar to a blistering 30C in some parts of the UK on Tuesday as the country basks in a baking start to September.
Brits are set to sizzle in a short Indian Summer as a three-day heat spell continues today.
The Met Office said some areas were edging close to recording an official heatwave this week as pupils head back to school.
On Monday, the maximum UK temperature was confirmed as 28.9C in Larkhill, Wiltshire, closely followed by the 28.8C recorded at Santon Downham, Suffolk, and 28.7C at Middle Wallop in Hampshire.
In Wales, the highest temperature was 27.1C at Usk in Monmouthshire, while the mercury reached 24C at Fyvie Castle in Scotland's Aberdeenshire and 22.2C at Ballywatticock in Northern Ireland.
Greg Dewhurst, a Met Office meteorologist, said central and eastern England were the likely areas that could experience a maximum of 30C on Tuesday.
He said central and eastern parts of England were "most likely" to record an official heatwave across Monday to Wednesday, but will only "just about make it".
He said: "We often get a warmer spell particularly early on in September.
"August was particularly cool... and cloudy, so this spell is the warmest spell of weather since July for the UK."
More widely across England and Wales, conditions will be in the mid-to-high 20s, while Scotland and Northern Ireland could see temperatures around 24C to 25C.
Mr Dewhurst added that low pressure moving in from the south west on Wednesday make it "less hot" in parts of Wales and Northern Ireland, but "hot air" will remain in central and eastern England and Scotland, bringing highs of 26C to 29C.
But temperatures are set to fall later in the week, with an increased risk of some heavy showers.
September has already beaten this August's highest temperature of 27.2C in the UK, which last happened in 2016.
The current warm weather follows the official end of summer, from a meteorological point of view, which is considered to be August 31.
UK Weather Forecast
Today:
Some drizzle in the far north and northwest, else dry and sunny for most areas after early mist, fog and patchy low cloud clears. Becoming hot inland over England and Wales. Risk of a shower in far south-west by evening.
Tonight:
A warm and humid night, with some mist and fog patches in the north, whilst thicker cloud brings some showers with risk of thunder to the south-west.
Wednesday:
Central, eastern and northern areas, dry with sunny periods, and becoming very warm or hot inland. Cloudier across western and some southern parts with showers, some heavy and thundery.
