Severe weather warnings could be imposed as torrential rain and strong winds are set to batter the UK, forecasters have warned.
As miserable May continues heavy downpours, hail storms and thunder are predicted to lash the country again on Tuesday.
And with more relentless downpours to come the washout spring of 2021 could see the wettest May on record, beating 1967 when 131.7mm of rain fell across the UK.
It's in stark contrast to last year's blistering sunshine that saw both the sunniest spring and driest May since records began.
Met Office forecaster, Sarah Kent, said that "changing climates" make changeable conditions and weather extremes "more likely".
But she said it was "too early" to predict if this month will be the wettest May on record.
Ms Kent said: "Over the next few days, large parts of the UK will see showery conditions with occasional torrential downpours, thunderstorms and even hail.
"Drivers should be very careful as quite a bit of rainfall could lead to some problems on the roads.
"I'd say it's going to be very unsettled, as some areas will see some sunshine, and be relatively warm, while it'll be chilly for those who see torrential rain."
Parts of the country could see weather warnings imposed before heavy downpours and unseasonable gales move in from Thursday, the Met Office said.
Those who are planning outdoor gatherings this week as coronavirus restrictions ease are being advised to think again due to "significant, windy weather" as the result of a low pressure system over the UK.
Temperatures in London and southern England will reach highs of 17C (62.6F), while the mercury in Wales, Scotland and northern Ireland will hit 15C (59F).
However, a deep area of low pressure will "hurtle" in from the west on Thursday.
Ms Kent added: "Wednesday will be the most favourable day of the week, but will be a quiet lull before a potent low pressure system arrives from the Atlantic bringing with it unseasonably strong winds and severe gales.
"Parts of the country could see weather warnings come in, as the winds and showers will hit large swathes of the country, particularly in western areas.
"Anyone planning outdoor gatherings should certainly keep an eye out for significant, windy weather and be sure to monitor the Met Office website for any warnings."
Five-day UK weather forecast
Today:
Starting mostly dry with sunny spells, but showers already in the southwest, developing more widely again, becoming heavy with risk of hail and thunder. Cloudy with rain or drizzle in the far north edging south into mainland Scotland.
Tonight:
Showers easing for many areas with clear spells developing, although further showers, some heavy in the south. Cloudier in the far north with rain at times.
Wednesday:
Heavy showers in south, developing again in other areas through the morning, but drier with more sunshine in southwest UK for the afternoon. Rain in central Scotland turning more showery.
Outlook for Thursday to Saturday:
Remaining very unsettled with some wet and very windy weather for many on Thursday and Friday, gales possible in the south. Less windy with showers Saturday and staying cool.
