Almost a month of rain is likely to hit parts of Britain on Friday.
Predictors issued a yellow warning between 8:00 am and 10:00 pm, which is likely to affect transport and cause flooding.
The warning applies to Wales, the northwest of England and the southwest of England. On the plateaus is expected to be the worst weather.
Acting forecaster Marco Petagna said that in some areas up to 80 mm of rain is possible.
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The average August rainfall in Wales is 107 mm and the August rainfall in the southwest is 90 mm – which means that almost a month of rain could fall on Friday alone.
"August can actually be a pretty wet month," he said.
Strong winds are also expected, with 30mph-40mph gusts likely around exposed coasts and hills.
Heavy rainfall can coincide with peak travel times in the afternoon and early evening, resulting in difficult driving conditions on important routes, the warning states.
Mr Petagna said that places outside the warning area will not miss the Friday rainfall.
"Much of England and Wales will have a wet day," he said, adding that it will rain sometime across the UK.
The forecaster said the weekend will bring sunshine and stormy showers, adding that things will look more positive next week.
"Especially in the middle of the week, the pressure builds up a bit," he said.