The UK could experience its hottest day ever next Sunday with the Met Office predicting temperatures may reach 40C.
Forecasters say there is a 30% chance that the current record for Britain's hottest day, the 38.7C set at Cambridge Botanic Garden in July 2019, could be broken.
The Met Office said next Sunday will see temperatures in the south of the country reach the mid to high 30s, with a 10% chance of reaching 40C.
It said "one or two" of its weather models have predicted highs of a staggering 43C on Sunday, but a forecaster told Yahoo News UK that figure was "very unlikely".
Watch: UK records hottest day of the year so far
However, there is an almost one in three chance that Britain could see its hottest ever day.
"Forty-three degrees is very unlikely," Met Office senior forecaster Becky Mitchell told Yahoo News UK on Sunday.
"One or two of the weather models have forecast it. But it is extremely unlikely.
"Temperatures next Sunday will be in the mid to high 30s. There is a 10% chance that temperatures will reach 40C.
"There is a 30% chance that the hottest day record will be broken."
On Sunday, the UK recorded a high temperature of 29.5C in London and the South East, while Scotland had its hottest day of the year so far, with the Met Office recording 28.9C in Fife.
The warm weather is expected to continue into this week.
"On Monday and Tuesday it will be 33C in the south," said Mitchell. "Things will cool off a little in the middle of the week, with high 20s forecast from Wednesday to Friday.
"On Saturday, temperatures will be in the 30s before Sunday's mid to high 30s."
Ireland also recorded its warmest day of 2022 to date on Sunday, with 25.6C reached at Shannon Airport in Co Clare.
The UK’s warmest day of the year so far was on 17 June, when 32.7C was recorded in Norfolk.
By 5pm on Sunday, Wisley in Surrey hit 29.5C, with temperatures in the high 20s across most of the country.
Met Office forecaster Dan Stroud said: “It’s been very warm across England today, temperatures staying in the high 20s.
“Interestingly, Scotland saw its hottest day of the year so far, while parts of Wales reached the mid-20s.
“Northern Ireland saw the coolest conditions, reaching highs of 23.4C, but most of the UK was still warmer than Mediterranean islands like Sardinia and parts of Turkey.
A heat-health alert has been issued for some parts of the UK next week, with those in affected areas advised to shade or cover windows and check on the vulnerable and the elderly.
Watch: Britons bask by the beach in Bournemouth heatwave