Office said.
"Plymouth is likely to see flooding," said Barry Gromett, weather forecaster at the Met Office.
"An area of low pressure is developing and intensifying over Western France which is headed towards Plymouth in the next few hours.
"This will bring with it heavy rain this evening and the majority of the rain will fall overnight through heavy showers," he said.
He added: "Plymouth is likely to get a degree of shelter from Northerly winds so the rain will get lighter towards the morning.
He said the area of low pressure will disperse through the early hours of the morning as it heads towards Humberside.
Tomorrow will be cool and cloudy with temperatures of 15 and 16 degrees C.
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