Britons are set to bask in the hottest day of the year on Wednesday, marking the start of a heatwave with temperatures soaring to 34C later in the week.
The Met Office and the UK Health Security Agency (UKHSA) have 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.
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.
Parts of the UK will also be warmer than Greek Islands Santorini, Mykonos and Zakynthos – as well as Los Angeles and parts of Barbados.
Greg Dewhurst, a Met Office forecaster, told the PA news agency: “The vast majority of England and Wales will see a lovely day on Wednesday, though slightly different in Northern Ireland and Scotland, which will see cloud and showers.
“It will be very warm in the South East in particular, with the temperature hitting a high of 28C, which would make it the warmest day of the year so far.
“This will then be surpassed on Thursday, with the mercury rising again to around 29C before reaching 33C and even 34C on Friday.
“So it’s going to be very warm as we move into the later part of the week.”
Forecasters have said some parts of England may experience a heatwave later this week, though it is likely to be 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.
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.
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.
An Environment Agency spokesperson said there is a low-risk of drought but warned further hot, dry weather could put pressure on some areas.
The British Red Cross encouraged people to protect themselves and to check in with vulnerable friends, family and neighbours during the soaring temperatures.
