The Met Office has issued a yellow weather warning for 14 hours of thunderstorms set to hit parts of the UK.
Thundery downpours are expected to lash through the west Midlands, east Midlands, north east England and Wales on Friday.
Northern Ireland, Dumfries, Galloway, Lothian & Borders are also areas covered by the warning.
Forecasters have warned of the risk of flooding to homes and businesses and road closures due to difficult driving conditions.
The Met Office said: "Heavy showers are expected across much of the UK on Friday.
"Within the warning area these showers and thunderstorms will be slow moving and may cause localised surface water impacts.
"Rainfall totals will vary considerably and not all locations will be affected by the heaviest showers.
"However, where the showers do occur there is potential for 20-30mm of rain in a short space of time and during the course of the day there is a chance that some places could see as much as 80-100mm build up."
Forecasters are predicting that weather conditions should improve by the middle of the month, when conditions look drier and warmer.
Though hopes of another heatwave have been dashed.
This comes after a yellow weather warning for storms came to an end last night - but weather experts now predict more downpours.
Flooding had already struck the Isle of Wight, with the Met Office reporting that up to 120mm of rain recorded near the town of Ventnor.
And last week Storm Evert battered parts of the country, producing ferocious gusts of winds close to 70mph across Cornwall and the Isles of Scilly.
Today the worst of the rain will emerge this afternoon, with some heavier spells centred around England.
By tomorrow there will be heavier rain and thunderstorms in some regions.
Marco Petagna, from the Met Office, earlier said: "Today and tomorrow, there will be a mixture of sunshine and showers for most across the UK.
"The weather will be more unsettled from Wednesday onwards. There's showers or longer spells of rain for most areas as we go from Wednesday into Thursday and potentially Friday as well."
The Met Office is predicting the weather will improve around August 15.
It said: “It will turn settled, though a few showers cannot be ruled out, especially in south eastern areas.
“This will bring drier weather, with sunny spells for most through to mid-August and temperatures trending above average.”
UK Weather Forecast
Today:
Many areas starting dry, the clearer areas rather chilly with the odd mist patch. Warming up with some sunshine this morning but scattered showers breaking out by afternoon, especially over England, the odd heavier one. Feeling pleasant in sunnier breaks.
Tonight:
Showers fading during the evening. Some cloudier areas persisting across England, where it will be mild but elsewhere clear spells may lead to rather chilly, possibly misty conditions.
Wednesday:
Some warm sunny spells at times for most areas. However, showery rain spreads across northwestern parts, before showers develop more widely by afternoon, heavy in places with the odd thunderstorm.
