The Met Office has urged people to stay indoors whenever possible, as the south of England is hit by a “huge pile” of storms.
As temperatures dropped from Friday’s highs of 32 degrees Celsius, the forecaster flashed warning that it had only used “a little” a few times before.
Meteorologists warned of “frequent lightning and some difficult driving conditions” on Saturday night, especially in parts of Sussex, Kent, Essex and Suffolk.
Meteorologist Becky Mitchell said a cold northern front was responsible for the sudden change in temperature.
“It looked like it had just entered summer, but now it’s cooler,” he said.
“Many places in the UK have seen a temperature drop of about 10 to 15 degrees in some places, which is massive.
“We have a huge pile of storms in the south west of England. There is potential that we could see some in the south east later tonight.”
The Met Office has only issued a lightning alert three times before, most recently in 2019.
“If you’re doing outdoor activities, go inside if you can; that’s the best advice really,” Ms. Mitchell said.
“Stay away from any power lines or anything similar that could be struck by lightning.
“If you are in an exposed place, stay close to the ground, away from anything that could be struck by lightning.”
While the weather seen on Friday is unlikely for the immediate future, it looks set to improve in time for the Glastonbury Festival next week.
Temperatures could reach 26 ºC on Thursday, before it cools down as the event ends on the weekend.
Friday sunbathing in Bournemouth
(PA child)
“It looks like the start of Glastonbury, especially on Wednesday or Thursday, is likely to be dry and sunny,” Mitchell said.
“It is likely that it will be a good time for anyone setting up your tent.
“Starting this weekend, starting on Friday, it looks like we could see more showers, probably some sunny, rainy moments.”
Although the maximum temperature was 32.7 ºC on Friday, the maximum on Saturday was 27 ºC in Herstmonceux, East Sussex, and there were showers in many places, with the Met office issuing a yellow warning for in the south-west of England as lightning and heavy rain approached.