The Met Office has predicted heavy rain in an official weather warning issued just a day after residents said a 'tornado' hit London.
The rain warning, which starts tomorrow and ends on Monday, spans south Wales and the south-west and south of England.
Forecasters have warned that more than three inches of rain could fall in places, with almost an inch possible in an hour.
The Met Office has also warned of possible flooding and travel disruption across the affected area.
The organisation's weather warning, which starts tomorrow afternoon, says: "Persistent rain, heavy and possibly thundery at times, will move across southern and southwestern areas of England and parts of south Wales through Sunday afternoon.
"It will persist into Monday morning, before easing. 20-40 mm is likely to fall quite widely across the area but a few places could see 60-80 mm over this period, including 15-25 mm within an hour. Such totals may cause travel disruption and some flooding."
It comes a day after residents claimed a 'tornado' hit Barking in East London, leaving a trail of destruction behind.
Videos showed trees falling in the street, as well as rubbish bins flying through the air and fences completely broken.
One resident wrote alongside their footage: "Tornado in Barking, East London. WOW."
Another posted a clip with the caption: "How is there a whole tornado in Barking."
A number of vehicles and homes were reportedly damaged, but Barking and Dagenham police said there have been no reports of casualties.
Officers said the event is a weather-related incident, but at this time it cannot be confirmed whether it was actually a tornado.
Sky News journalist Kiran Bhangal tweeted: “Just experienced a tornado in Barking east London. Dozens of cars and homes damaged.
“Police and fire crews on the scene. Very scary indeed.”
Barking and Dagenham police said: "Police were called at around 1920hrs to reports of damage caused to roofs, electrical equipment, street furniture and vehicles in Hulse Avenue and some surrounding roads in the #Barking area.
"This is a weather-related incident, during which there was a lightning strike.
"In addition to the lightning strike, we have seen reports of a tornado but cannot confirm this.
"There are no reports of any casualties.
"Officers are liaising with the local authority to ensure support is available to anyone affected by damage to property."
