Motorists are being urged to adjust their driving style if they get caught in one of the thunderstorms expected to hit Britain.
The AA warned “extreme caution is advised” as roads could become “hazardous” due to flooding.
Some areas could be deluged by up to 50mm of rain in two hours on Wednesday and more than 60mm of rain in two to three hours on Thursday, according to the Met Office.
The Highway Code says stopping distances in wet weather are “at least double” compared with dry conditions as tyres have less grip on the road.
It recommends that drivers should keep “well back from the vehicle in front” and take extra care around pedestrians, cyclists, motorcyclists and horse riders.
If steering becomes unresponsive – likely because water is preventing tyres from gripping the road – motorists are advised to ease off the accelerator and slow down gradually.
AA patrol of the year Chris Wood said: “If you must travel, reduce your speed to account for the conditions and leave plenty of space behind other vehicles.
“Allow extra time, as it’s likely your journey will take longer than usual, and ensure you have plenty of fuel or electrical charge.
“In a thunderstorm, water can quickly run off the road, causing flash flooding.
“It only takes one incident to cause long tailbacks, so keep tuned to local traffic reports and reduce your speed as appropriate for the conditions.
“Never risk driving through floodwater and if you find yourself aquaplaning, ease off the accelerator to slow down gently.”
RAC spokesperson Alice Simpson said: “Sudden downpours have the potential to quickly make the roads far more dangerous places – a fact illustrated by official figures that show an average of 1,660 people are killed or seriously injured every year as a result of bad weather making roads slippery.
“In 2022 alone, the most recent year for which data is available, there were 53 such fatalities.
“Our patrols are also expecting a 75% rise in calls from drivers whose vehicles become ditched or bogged due to intense rainfall.”
