Flood alerts and yellow weather warnings are in place as thunderstorms move across parts of the UK.
Dowdeswell Reservoir in Gloucestershire had seen around half its average monthly rainfall in four to five hours by Wednesday afternoon.
Seven Environment Agency (EA) flood alerts were in place at that time, covering riverside areas in Devon and Haywards Heath in West Sussex.
A yellow Met Office warning for thunderstorms was activated at 11am on Wednesday in the east, south-west and south-east of England, including London, and it will run until 8pm.
It also spans the East and West Midlands, Yorkshire and parts of Wales.
Meanwhile a yellow warning for rain is in place from 12pm to 9pm in north-east Scotland.
Some locations in the thunderstorm warning zone could see up to 30mm of rain in an hour, bringing a risk of surface water flooding.
Around 30mm will fall quite widely in the rain warning area and coastal sites could see up to 80mm, the Met Office said.
Ellie Glasyer, a Met Office meteorologist, said: “If everything comes together and you see the right shower in the right place, you could see half a month’s rainfall within a couple of hours.
“With the nature of a thunderstorm warning, and the nature of showers, not everywhere will see that much rainfall – some people might obviously not see any rainfall within that warning area.
“But there is a chance that there could be some heavy downpours, and some hail and thunder mixed in with those showers, as well as some strong gusty winds and some lightning.”
Gusts of up to 45mph had been recorded by Wednesday afternoon.
Rush-hour commuters could experience delays, transport disruption and difficult driving conditions given the timings of the thunderstorms, the Met Office warned.
Another yellow thunderstorm warning is in place from 2am to 5pm on Thursday for the majority of England and Wales.
Spray and sudden flooding could produce challenging conditions on the roads and there is a chance that homes and small business could flood quickly, the Met Office said in that warning.
Dane Broomfield, from the EA, said: “Persistent heavy rain and thundery showers mean minor surface water flooding is probable across parts of England today, with significant impacts possible but not expected on Thursday.
“Environment Agency teams will be out on the ground and supporting local authorities in responding to surface water flooding.”
The duty flood manager added: “We urge people not to drive though flood water – it is often deeper than it looks and just 30cm of flowing water is enough to float your car.”
