Sadiq Khan issues dead of night flash flooding warning as thunderstorms threaten London

Yellow thunderstorm warnings have been issued for London on Wednesday, with a threat of flooding in some areas.

Forecasters at the Met Office are predicting “a band of heavy showers and thunderstorms” will hit the capital on Wednesday morning and further showers and storms may break out in the afternoon.

There is also a chance of “intense” downpour with an expected 20-30mm of rainfall in less than an hour. In some areas, there may even be 40-50mm of rainfall within two to three hours, which could lead to some surface water flooding, the warning said.

The warning is in place from 3am to 10pm on Wednesday

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Many places will miss the showers, but others could see large hailstones and frequent lightning.

The showers are expected to ease during the evening, with the warning in place between 3am and 10pm.

Yellow flood warnings mean that there is a small chance that businesses and homes could experience flooding.

This could lead to cancellations of public transport services and some road closures.

The hard ground after the sustained hot weather is expected to increase the risk of flash flooding.

There is also a small risk of power cuts.

The Met Office is advising that Londoners check if their location is at risk of flash flooding and to consider preparing a flood plan if so.

For those who find themselves outside during thunderstorms, it is advised to find safe enclosed shelter, like a car. But you should not seek shelter under a tree or other structures that might be struck by lightning.

The warning has a very low likelihood of happening, but could have a medium impact on affected areas.

As much as 20-30mm of rain could hammer down on London in one hour

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In addition to Greater London, other areas impacted in the south east of England include Hampshire, Kent, Medway, Milton Keynes, Surrey, Reading, Windsor, and Buckinghamshire.

Parts of the east of England, East Midlands, North West and South West of England could also be affected, as well as parts of Wales and the West Midlands.

The rain comes after London experienced one of its driest summers on record. Millions of people were placed under hosepipe bans as London was declared to be in drought, while green spaces and parks across the capital were scorched by the blistering heat.

London also saw a spate of wildfires break out amid the dry conditions. For many, the rainfall will be a welcome reprieve to the scorching summer.

Thunderstorms frequently happen after periods of hot weather when high temperatures warm up the ground and air. As the warm air rises and condenses, it unsteadies the atmosphere, creating thunderstorm clouds. These clouds produce hail, thunder, and lightning.