Six weeks’ worth of rain is set to pour down in just 12 hours when a so-called “megastorm” hits the UK on Sunday.
A 200 mile area across the UK, which includes London, is set to be affected by the deluge, while thunder and lightning have also been forecast.
The Met Office weather warning in place with heavy rain to batter much of the country on both Sunday and Monday.
“Summer has now officially come to an end, and it ended with a bang for some of us,” Met Office meteorologist Jonathan Vautrey told the Mirror.
"We've seen some very heavy showers and thunderstorms spreading their way across southern areas of England, into parts of Wales as well during the course of today."
The “megastorm” will be hardest felt on Sunday and comes on the back of balmy weather on September 21.
However, a nice day on Saturday led to storms overnight with many Londoners waking up to thunder and lightning.
Met Office meteorologist Becky Mitchell said thunderstorms could continue in the days ahead. The weather will remain unsettled over the next few days with “potential for some localised flooding”, she added.
BBC Weather has also forecast thunder and lighting for all hours up to 10pm on Sunday in London with further rain forecast for Monday.
The forecast reads: “Today will be unsettled with cloudy skies and spells of rain to start.
“These will clear to sunny spells and scattered heavy showers in the afternoon. Risk of thunder. A cooler day.”
