More heavy rain and gusts of up to 50mph will see the weekend washout continue following weeks of hot, dry weather.
A deluge of rainfall and a dramatic drop in temperatures brought an end to the summer heatwave for many on Saturday.
More than a month's worth of rain fell at Belfast International Airport, with the torrential downpours causing flooding and traffic disruption across the region.
A yellow weather warning for rain was in place for western parts of Scotland on Saturday, while a warning for wind and rain covers Wales and the south of England on Sunday.
Winds of up to 50mph are forecast for exposed coasts and hills with as much as 80mm of rain possible in the Brecon Beacons and Dartmoor, the Met Office said.
Flooding is possible and large waves are likely in coastal areas, the forecaster added, warning of potential damage to tents and other temporary structures.
Saturday was the first day this month that nowhere in the UK reached at least 25C, the forecaster added, marking a 10-degree drop from Thursday which saw the hottest day of the year so far.
Cavendish in Suffolk and Weybourne in Norfolk enjoyed Saturday's UK high of 24C.
As thunderstorms brought the first significant rainfall for weeks to the UK, Belfast International Airport saw 88.2mm in just a few hours - above the July average for the entire region, which sits at 81.2mm.
Meteorologist Sarah Kent said that, unlike thunderstorms in many other parts of the UK, those in Northern Ireland came as a result of low pressure, rather than directly relating to the recent heatwave.
Short Ferry in Lincolnshire had 41.8mm of rainfall in one hour on Friday, nearing the county's monthly July average of 55.8mm.
Heavy, thundery showers will continue as changeable weather replaces the hot spell much of the UK has endured for weeks.
"It's a very unsettled weather picture across the whole of the UK," said meteorologist Sarah Kent.
She said campers especially should take heed of the windy weather.
She said: "The warning is in place particularly for holidaymakers who are out camping or towing their caravans, they are going to see some very strong gusts."
Sunday's highs are expected to remain much nearer normal for the time of year, with the south of England likely to see the mercury struggle to climb higher than the low 20s in southern England.
While some will have welcomed the rain and the cooler temperatures, those keen to catch a glimpse of the blood moon, the longest lunar eclipse of the 21st century, on Friday were disappointed by cloud cover.
Holidaymakers were beset by delays and cancellations due to the extreme weather on Saturday.
A number of flights were affected, and travellers suffered long delays waiting for ferries and cross-Channel trains.
Two bodies were recovered on Saturday in separate incidents following concerns people had got into difficulties in water.
The body of a 15-year-old was recovered in Essex.
Police said the teenager, provisionally named as Ben Quartermaine, was found near Clacton Pier after a search which began on Thursday.
In Bedfordshire the body of a man aged in his late 20s was recovered from the Great Ouse river after reports someone had got into difficulty there on Friday afternoon.
A man's body was recovered from the Jubilee River in Slough on Thursday, Thames Valley Police said, and on Friday a body was found by police in Warwickshire searching for a 17-year-old boy who disappeared after getting into difficulty in a quarry lake.
The heatwave, which last week contributed to a "high" air pollution alert being issued for London, is set to return towards the end of next week.
"We will see more settled conditions across southern areas by the weekend, with temperatures creeping back towards 30C in places," said Ms Kent.
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