Brits have been warned to prepare for what could potentially be the hottest June day since records began as forecasters predict searing heat will wash over the UK.
Temperatures will sizzle from Wednesday, which will see highs of 28C in parts of the South East.
It would make it the hottest day of the year so far, eclipsing the 27.5C set in mid-May at Heathrow.
Friday is set to be even hotter, with temperatures of 34C predicted for some parts of the South East.
But temperatures would have to rise a bit further for any records, which date from 1884 to be broken, with the previous highest being set in Southampton Mayflower Park on 28 June 1976, when temperatures reached 35.6C.
Forecasters have warned of rising temperatures this week, and the Met Office has issued a level 2 heat-health alert for a large part of southern and central England, with a level 1 alert in place for northern England.
Parts of the UK will also be warmer than the Greek Islands of Santorini, Mykonos and Zakynthos – as well as Los Angeles and parts of Barbados.
Met Office deputy chief meteorologist, Dan Rudman, said: “Temperatures will rise through the week, becoming well above-average by day by Friday when many parts of the southern half of the UK are likely to reach 30C or even 33C in isolated spots.”
“This is the first spell of hot weather this year and it is still unusual for temperature to exceed these values in June.
"Many areas will also see some warm nights with temperatures expected to be in the mid to high teens overnight.”
What is a heatwave?
A heatwave is defined as three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold.
The threshold varies in each county.
According to the Met Office, some parts of England may perhaps meet these heat wave criteria it looks like this spell of warm weather will be relatively short-lived.
On the four-level heat-health alert scale, which is designed to help healthcare workers manage through periods of extreme temperatures, level 1 is the lowest warning and is the minimum state of vigilance used during the summer months.
Level 2, called alert and readiness, is triggered as soon there is a 60% risk that temperature thresholds will be reached in one or more regions on at least two consecutive days and the intervening night.
Agostinho Sousa, head of extreme events and health protection at the UKHSA, said: “During periods of hot weather it is especially important to keep checking on those who are most vulnerable, such as older people and those with heart or lung conditions.
“Make sure to look out for signs of heat exhaustion and follow our simple health advice to beat the heat.”
Charity Age UK is urging elderly people to take some simple precautions, particularly if they have breathing problems or a heart condition.
Caroline Abrahams, of the charity, said: “Older people can be at risk of dehydration and overheating when it gets hot, especially if they live somewhere that is hard to keep cool, so it’s a good idea to let people know if you have any concerns about yourself, especially if you live alone.
“For the rest of us, checking in on older relatives and neighbours is a nice idea – for example, you may have an extra fan you can lend, and the offer of an ice cream when it is sweltering will usually be appreciated too.
“Taking simple steps to keep cool during the hottest parts of the day is a good idea.”
She advised elderly people to remain indoors, wear light clothing and drink plenty of water during the warmest times in the day.