Some areas of the UK received more than half a month’s worth of rain in just one hour on Tuesday, as flash floods hit parts of Cornwall and Kent.
The heaviest rain recorded by the Met Office on Tuesday was at Reading University, where 1.4in (36mm) of rain fell between 9pm and 10pm.
This is more than half the average rainfall expected over the entire month of July, which is usually around 2.3in (57.5mm).
But flash flooding in Cornwall on Tuesday night was not reflected in the amount of rain recorded by the Met Office in the area.
— Mullion Fire Station (@MullionCFRS) July 18, 2017
Forecaster Craig Snell told the Press Association that the most rain water gauges in Cornwall recorded was 0.08in (2mm) an hour at 2pm on Tuesday.
“Their gauges did not record that much at all,” he said.
Despite these figures, flash floods hit the Cornish coastal village of Coverack, where 50 properties were affected and several people had to be rescued from their homes.
“(Flash floods) can be very, very localised,” said the forecaster.
And Mr Snell said local geography affects whether heavy rain turns into flash floods.
“There are a lot of local factors,” he said, “If it’s more hilly, which is what we saw in Cornwall, water moves quicker.
“The amount of rainfall in Cornwall might not necessarily cause (flash floods) somewhere else.”
Crazy storm in Tunbridge Wells. Never seen so much lightning and heard so much thunder. pic.twitter.com/kS6VaISQhG
— David K E Morgan (@dkemorgan) July 19, 2017
Water had to be pumped out of several properties in Tunbridge Wells in Kent, and a nearby gauge in Sutton Valence recorded 0.6in (15mm) of rainfall between 2am and 3am on Wednesday.
There were also reports of storms in Shoreham-by-Sea, with nearby Shoreham Airport measuring rainfall of 0.8in (20mm) an hour at 1am.
Although there is no strict definition of flash flooding, Mr Snell said to qualify there needs to be a large amount of rain falling during a short period of time.
“It needs to be more than 10mm (0.4in) in the hour to start causing some issues on the roads for example,” he said.