London weather: Met Office issue thunderstorm alert, hour-by-hour temperature forecast, how long will it last?

Monday night was offically confirmed as the warmest night since records began in the United Kingdom.

The Met Office has issued a yellow status severe weather warning of a thunderstorm for London.

The alert was issued on Tuesday and will be active between 1pm and 9pm tomorrow (Wednesday).

“Heavy showers and thunderstorms are expected to develop across central, southern and eastern parts of England on Wednesday afternoon,” said the Met Office on its official website on Tuesday afternoon.

“Whilst most places will see only small amounts of rain there is a chance of some isolated heavy downpours and lightning.

“Where these occur a few sites could see 20-30 mm in an hour and 50 mm in three hours.”

What to expect?

  • Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
  • Spray and sudden flooding could lead to difficult driving conditions and some road closures.
  • There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.


An exceptionally hot day will develop after a very warm start for many, with lengthy periods of strong sunshine and a southerly wind. The sunshine may turn hazier in the west later, with isolated gusty showers or thunderstorms developing. Maximum temperature 40 °C.


Another warm night, with isolated showers or thunderstorms gradually clearing into the North Sea. Probably becoming cloudier from the west overnight, perhaps with the odd spot of rain later. Minimum temperature 17 °C.


Still very warm, but cloudier overall with outbreaks of rain. Heavier, more showery bursts may develop in places later, potentially thundery at times. Breezier than recently, and gusty around showers. Maximum temperature 28 °C.

Outlook for Thursday to Saturday:

More seasonable temperatures are expected through this period. Sunny spells and showers Thursday may give way to more widespread thundery showers Friday. Probably warmer again Saturday, with sunshine and showers.