Yellow weather alerts have been issued by forecasters as most of England and Wales is expected to be hit with heavy rain.
The Met Office has warned prolonged rain on Friday going into Saturday morning may lead to flooding and severe travel disruption.
The 12-hour warning is set to bring some flooding, delayed transport services and difficult driving conditions due to spray and flooding on road surfaces.
Outbreaks of rain are forecast to arrive from the west during the morning, becoming heavier and more persistent during the afternoon.
In the wettest spots, there may be up to 70mm of rain in parts of the South West.
Meteorologists report that persistent rainfall will continue throughout Wednesday, with the heaviest downpours expected in Wales, southwest England and northern Scotland. Some areas could experience coastal gales, particularly in northern regions.
Heavy rain has been forecast
|PA
The area of rain set to be covered by heavy rain over the weekend
|MET OFFICE
Chief forecaster Neil Armstrong cautioned that the nation faces "an unsettled week of weather" with frequent heavy rainfall and gusty winds.
He warned of potential flooding due to already saturated ground conditions from recent wet weather.
Forecasters have announced an additional weather alert for Friday extending into Saturday morning, encompassing a vast swathe of England and Wales.
The warning predicts widespread accumulations of 30 to 50 millimetres of rainfall, with certain locations potentially receiving between 60 and 80 millimetres.
People walking along the Dawlish sea wall in Teignbridge, Devon, which is expected to see heavy rain
|PA
LATEST DEVELOPMENTS
East-facing hillsides in southeast Wales could see rainfall exceeding 100 millimetres during this period.
Strong easterly winds will accompany the deluge, which begins Thursday evening and intensifies throughout Friday before gradually diminishing on Saturday morning.
The Met Office spokesperson stated that "heavy and prolonged rain during Friday into early Saturday may lead to some flooding and disruption" across the affected regions.
The alert zone stretches from South Yorkshire and Lincolnshire southwards through the Midlands, extending to areas just below the M25. Western regions of Wales escape the warning, whilst coverage extends westward into Devon.
Heavy rain is expected to hit London this weekend
|PA
Greater Manchester and the North West are forecast to avoid the most severe conditions.
However, the combination of this incoming rainfall with already waterlogged ground raises concerns about surface water and river flooding across southeast Wales, the Midlands and southern England.
Current conditions show two distinct bands of precipitation affecting the country. Northern Scotland experiences one zone of wet weather, whilst southern and central England contend with another, leaving a narrowing corridor of drier conditions between them.
Temperatures will vary significantly across the country, with southern regions experiencing mild to very mild conditions reaching 14 to 16 degrees Celsius.
Our Standards: The GB News Editorial Charter