The southern UK is continuing to swelter on Monday, while the North is feeling a cooling relief from the heatwave.
Sunday was the hottest day in Britain for almost 130 years
However, temperatures are unlikely to hit the record reached on Sunday when Gravesend, Kent soared to 38.1C (100.6F) - the hottest day ever recorded in Britain.
Temperatures are set to reach 33C (91F) in London and 30C (86F) elsewhere in the South East, while in Scotland it will be 22C (72F), 26C (79F) in Wales and 23C (73F) in Northern Ireland.
Some parts of the country may also get scattered
showers, with torrential rain and thunder storms that dulled Sunday in northern England and the Midlands likely to return.
But shoppers are banking on the heatwave continuing well into this week.
Supermarket groups have reported a rush on barbecue gear, salads, beer and soft drinks.
And grocers have brought in more meat, fruit juices and bottled water to meet demand.
Sales of barbecue fuel reportedly hit record levels at Tesco during the weekend.
The supermarket chain also sold 150,000 litres of sun cream.
And Asda sold two million
tubs of ice cream.
But the heatwave is bad news for some.
Bookmakers lost more than £300,000 to punters who backed the record-breaking temperatures, according to Ladbrokes spokesman Warren Lush.
People used London's fountains to cool down
The temperature record was first broken when Heathrow airport registered 37.9C (100.2F), the hottest day since records began about 130 years ago in 1875.
The previous record was 37.1C (98.8F), recorded at Cheltenham in 1990.
The heat has also hit other sections of industry.
Indoor shopping centres have had fewer customers, with
department stores and clothing shops among the hardest hit.
Other companies have seen productivity fall.
And speed restrictions on railways and increased road congestion have made many commuters late for work during the past week.
On Monday afternoon Network Rail said the only remaining speed restriction was a 60mph limit between Chelmsford and London's Liverpool Street.
On Sunday a man out fishing off Hartlepool Marina died when his boat was smashed to pieces.
Another man, also from the Hartlepool area, who was in the boat with him is being treated in hospital for hypothermia.
winds also downed trees and power lines.
A flash flood in Middlesbrough forced the accident and emergency department at Middlesbrough General to relocate after its basement flooded.
"It was chaos," said Bill Murray from South Tees Hospital NHS Trust.
"We had a lovely day, it was blue skies and into the 30s then all of a sudden it just went like midnight, just black, the wind came up and torrential rain.
"I can't remember in my living time such a flash flood like it.
"Water just cascaded through every entrance, down the stairs."
A children's ward damaged by heavy rain and winds is expected to remain closed for a week - 21 patients have been moved to another ward at the University Hospital of North Tees in Stockton, Teesside.
The University Hospital of Hartlepool also experienced water
Also in Middlesbrough, a 61-year-old man died
from a suspected heart attack as he ran to take shelter from the deluge.
And the city's Cleveland Shopping Centre was evacuated after flooding
Lightning injured 20 people, including 14 people struck at a leisure centre in Birmingham on Sunday.
One woman was directly hit and had a heart attack, while others were treated for burns, eye injuries and shock.
In Lancashire, two Brownies were slightly injured when lightning struck between them at a camp near Blackburn.
'No spare sand'
Another six people were injured when lightning struck at an agriculture show in Corley, Warwickshire.
In Birmingham, more than 60 firefighters fought a large fire at factory units
struck by lightning during the storms.
Roads leading to the coast were jammed on Sunday and the beaches crammed as people tried to cool off.
At Bournemouth in Dorset, the coastline was crammed to capacity with about 100,000 sun lovers and "no spare sand".