Thunderstorms are set to deluge parts of the UK over the next four days, according to the Met Office.
Yellow weather warnings for thunder and heavy rain have been issued across areas in England, Wales, Scotland and Northern Ireland.
Forecasters believe some areas, particularly the north west of England and north Wales, could see as much as 80-100mm of rain on Friday.
There are no flood warnings in place over the four nations, but this could change due to the intense showers expected to batter the country over the weekend.
Met Office spokesman Oli Claydon said: “We’ve got an area of low pressure that’s moving in from the west from the Atlantic and across the UK which is going to bring very unsettled conditions across the weekend.
“The weather warnings have been put in place from today lunchtime right the way through to Saturday morning at around 9am.
“It’s going to start tomorrow with rain in Northern Ireland and then thunderstorms are going to extend across the central slice of the UK.”
He added: “We could see 20-30mm of rain in a short space of time on Friday. With some places even seeing between 80-100mm, most likely in north Wales and north west England.”
There has been heavy rain in parts of north Wales and northern England on Wednesday.
But the showers will mostly die out until Thursday, when Northern Ireland will begin to bear the brunt of the thunderstorms.
Bands of rain will then move northeastwards across the UK, becoming heavy in places with downpours and strong winds.
The worst of the wet weather, however, will be seen throughout Friday and into Saturday morning when the weather warnings stretch from Perth in Scotland down through to the Midlands and across north Wales. Those areas will likely see longer spells of thundery rain and lower temperatures.
The driest areas will be in the south east of the UK.
And although the turbulent weather looks set to continue for a time, the Met Office has said there are early signs that temperatures could start to increase through next week.
The UK recorded its joint fifth warmest July on record this year after a heatwave that saw the first extreme heat warning.
In contrast, the second half of the month saw some areas hit by intense downpours which caused flooding.