Heavy thundery rain is expected to strike on Thursday with "wet and windy" weather continuing into the weekend.
The Environment Agency has put a flood alert in place for Keswick, Cumbria as overnight temperatures plummeted to 4C in parts of the UK.
BBC forecaster Susan Powell described the upcoming weather as a "mixed bag" with temperatures lower than average for the time of year.
"All of us are going to see some rain at some stage - there will be some sun at times too but rather windy weather, especially Friday and into the weekend and our temperatures distinctly disappointing," said Ms Powell.
Thursday is expected to be "one of the better ones" but showers will hit in the afternoon - "not everywhere will see rain but where we do it could be heavy and thundery", said the meteorologist.
Temperatures today could reach the high teens, but will feel cooler where it rains - a far cry from last week's 33C sizzler.
On Friday, East Anglia and the south east are likely to be the only areas to stay dry and could see highs of 21C but everyone else will feel the force of "low pressure barrelling its way in" meaning "persistent rain".
"As for the weekend though, low pressure still in charge with some wet and windy weather on the way," added Ms Powell.
It comes after Sunday was confirmed the wettest June day on record, according to the Met Office.
There was 212.8mm (8.37in) of rain at Honister Pass in the Lake District, the equivalent of 10 weeks' rainfall in one day.
That beat the previous record for the wettest June day, 208.4mm (8.2in) in 2012, also recorded at Honister Pass.
Meanwhile, bookmakers have slashed the odds on it being the hottest July on record as UK temperatures are set to soar again.
The odds have been cut from 5/1 to 5/2 on it being a record-breaking July.
Alex Apati of Ladbrokes said: "Brits will soon be sizzling in record-breaking July sunshine if the latest odds are anything to go by."
Despite the rainy start, the Met Office long range reports do suggest July will settle as the month goes on with another potential heatwave on the cards.
UK 5 day weather forecast
Today:
Cloudy across central parts with rain gradually dying out. Sunny spells with scattered heavy showers and isolated thunderstorms across southern areas. Mostly dry across northern areas.
Tonight:
Showers across England and Scotland easing and gradually dying out. Chilly in the north before more widespread rain and strengthening winds arrive in the northwest later in the night.
Friday:
Rain and strong winds in the northwest gradually spreading southwards. East and south England becoming increasingly cloudy but mostly dry. Perhaps brightening up for a time in west Scotland.
Outlook for Saturday to Monday:
Cloudy and breezy with rain at times on Saturday. Feeling humid in the south. Rain clearing southwards on Sunday. Fresher conditions following with some showers.
