Thunderstorms could cast a shadow over plans for a summer weekend of camping, festival-going or lazing on the beach.
The Met Office has said that the heatwave will be replaced with unsettled and thundery conditions for southern and central areas, with yellow weather warnings in force.
A thunderstorm warning is in place until 10pm on Saturday, with the possibility of heavy rain that could cause disruption and flooding.
The warning covers southern England and Wales, potentially disappointing anyone who hoped for a dry, sunny trip to the coast.
Music lovers at the Latitude festival in Suffolk will be hoping they can avoid a muddy mosh pit while anyone with camping in mind may want to pack wisely.
A yellow wind warning for the southern coastal counties of England, lasting from Friday afternoon until midnight, was issued due to strong north-easterly winds of up to 55mph.
Forecasters warned that this could cause tricky driving conditions, especially for larger vehicles or those towing caravans.
Saturday is likely to see frequent lightning, thundery rain and continued strong, gusty winds in the areas covered by the thunderstorm warning.
Some sunshine in the north on Saturday, but heavy showers and ⚠️ #thunderstorms ⚠️ for parts of the south
Stay up to date with the latest weather warning info 👉 https://t.co/QwDLMfRBfs
— Met Office (@metoffice) July 23, 2021
There is also a risk of large hail falling in a few places, and where there are heavy downpours there could be up to 35mm of rain falling within an hour, bringing the risk of flooding.
A second yellow warning for thunderstorms shifts the focus away from the far South West but still covers much of southern England, parts of central England and the far south east of Wales, running from 9am on Sunday morning through to midnight.
Forecasters said some of the heaviest showers are expected in the South East in the morning, before falling more widely across the warning area as the day goes on.
There is the potential for up to 80-100mm of rainfall to build up in some places over the course of the day, which will bring a risk of flooding and some poor driving conditions with surface water likely on roads.
Met Office principal operational meteorologist Frank Saunders said: “The warnings in place over the weekend show a marked shift in the weather pattern for many southern areas as low pressure moves in, with potential impacts for business and the public.
“This more unsettled weather brings a risk of torrential downpours and flooding in some places.
“However, areas further north will cling on to see some fine weather through the weekend, although not quite as hot as recently.”
Forecasters said the unsettled weather looks set to continue early next week, with more persistent rain expected for much of the UK.
A Met Office amber warning for extreme heat had been in place for England until midnight on Thursday.
The country reached its hottest temperature of the year on Tuesday when 32.2C was recorded at Heathrow Airport in west London.