Heavy rain is expected (Image: PA)

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Flash flooding is expected to swamp homes as severe thunderstorms batter parts of London and the Home Counties, the Met Office has warned.

The national forecaster issued an amber "danger to life" weather warning, saying as much as 4ins of rain could fall within the space of just a few hours.

It said flooding of homes and businesses is "likely" and "could happen quickly" by early evening.

While heavy rain and flooding pose the biggest threats, lightning strikes could cause damage to buildings and hazardous driving conditions are expected in downpours.

Send your photos of flooding or severe weather to [email protected]

An amber warning for thunderstorms is in effect until 7pm on Sunday
(Image: Met Office)

A line of torrential showers and thunderstorms stretched from Surrey to western Essex as of 3pm and it was likely to move slowly through the area.

The amber warning for thunderstorms was due to end at 7pm on Sunday.

It was issued for the following areas:

  • Essex
  • Hertfordshire
  • Bracknell Forest
  • Buckinghamshire
  • Greater London
  • Slough
  • Surrey
  • Windsor and Maidenhead

The Met Office warned: “Heavy showers and thunderstorms have formed in a line stretching northeast from Surrey towards western Essex.

“This line will remain fairly slow-moving through the coming hours, while individual showers or storms tend to move southwest along it.

“Each shower could bring 20-40mm (about 0.8ins to 1.6ins) of rainfall within an hour, with isolated locations that experience several showers perhaps seeing 75-100mm (about 3ins to 4ins) of rainfall within the space of a few hours.

“Although some isolated lightning is likely rainfall and the associated surface water flooding are expected to bring the greatest impacts.”

The Met Office also warned:

  • Flooding of homes and businesses is likely and could happen quickly, with damage to some buildings from floodwater and isolated lightning strikes.
  • Where flooding or lightning strikes occur, delays and some cancellations to train and bus services are likely.
  • Spray and sudden flooding probably leading to difficult driving conditions and some road closures.

A separate yellow warning for thunderstorms covers a wider area, stretching from Devon to Norfolk.

That warning, which is in place until midnight, says: "After early rainfall over southeastern England, showers and thunderstorms are likely to develop more widely during the afternoon.

"The focus of torrential downpours will probably be over parts of East Anglia and southeastern England and, perhaps, more locally across some southern coastal counties further west.

"Hail, gusty winds and lightning may prove additional hazards.

"Some areas, particularly in the west, may largely avoid the heaviest showers.

"Rainfall amounts will vary considerably from place to place, but hourly totals could approach 30-40mm in some places, with a few locations perhaps picking up 60 to 80mm from successive showers and storms."

On Saturday, a lightning strike caused the roof to collapse and flames to spread through two semi-detached houses in Andover, Hampshire, as a week-long heatwave came to an end.