The first heat health warning of the year has been issued - a rare amber level alert - with six regions of Britain set to be affected.
Forecasters are predicting temperatures of up to 30C this weekend, in what would smash the current 2023 hottest day of the year record.
Parts of the UK will be hotter than Marbella, Ibiza and Tenerife thanks to a "plume of warm air" moving in from the south.
It comes as the Met Office has issued a yellow weather warning for thunderstorms in England and Wales from 9am Friday until Monday morning.
It is expected that some parts of the UK could see 30-40mm of rain in an hour during parts of Saturday, with hail also expected to hit the UK on the same day.
Forecaster Oli Clayden said: "This is going to be the warmest weekend of the year, which is to be expected as we go into summer.
"This weekend will also see hail mixed in with strong gusts of wind and rain hit parts of the country."
See below for which regions will get the hottest and when
Scotland
Friday afternoon will be sunny and warm after some early cloud - with temperatures reaching highs of 22C in parts.
It is expected to be very warm and sunny on Saturday with potential for 24C by around 4pm in the Scottish Highlands.
Sunday and Monday sees a risk of heavy and possibly thundery showers breaking out - though temperatures could reach similar highs again.
North East
Low cloud will clear by Friday afternoon with long sunny periods - and highs of 18 or 19C towards the centre of the region around York.
It is likely to be even hotter on Saturday, with temperatures reaching 24C in parts.
Sunday and Monday will see sunny spells potentially interrupted by heavy, thundery showers.
North West
Friday is due to be warm with highs of 23C in and around Liverpool by 4pm, though slightly breezier than of late, especially on the coasts.
Saturday is expected to be even hotter, with winds easing and temperatures peaking at 27C in Preston as humidity rises overnight.
Lots of dry weather although the chance of heavy showers, perhaps thundery at times across Sunday and Morning - but highs in the mid 20s.
Wales
Temperatures are set to peak at 26C tomorrow afternoon in the likes of Cardiff and Swansea, with plenty of sunshine - though a risk of showers in the south.
It will feel even warmer as the mercury rises on Saturday and the wind eases, though actual temperatures may dip a digit or two.
Despite the dry weather, there is a chance of heavy showers, perhaps thundery in the latter stages of the weekend.
Midlands
Friday is set to be warm with plenty of sunshine, though a breezier day of late and highs of 25C by 4pm in Worcester.
Saturday afternoon will then see 27C in the likes of Leicester, Stratford-upon-Avon and Coventry.
There's a chance of heavy showers - possibly thundery - as the weekend goes on, though temperatures will stay in the mid 20s on Sunday and Monday.
London and South East
Prolonged periods of sun are forecast on Friday afternoon, with readings of 24C likely in London and 26C in Brighton at around 4pm.
Saturday will see things ramp up as the English capital is hit by 28C, with humidity skyrocketing throughout the region.
There is also the chance of heavy and thundery showers across the weekend with temperatures remaining in the mid to high 20s on Sunday and Monday.
South West
Cloud is likely to gradually increase through the day tomorrow with a few showers possible in the afternoon and plenty of wind, as temperatures peak in the likes of Yeovil at around 27C.
Saturday is expected to feel very warm as winds ease and temperatures stay in the mid 20s for much of the region.
Sunday will see things cool slightly, then pick up again on Monday to around 24C - with a chance of heavy showers, as per the rest of the country.
