More than a month's worth of rain could fall within two hours on Hitchin later this week, causing flash floods, the national weather service has said.

Yellow thunderstorm warnings have been put in place by the Met Office up to Thursday with many areas including Hitchin set to be affected by severe thunderstorms, with a chance of 'torrential downpours'.

"Even in just a couple of hours we could see 80mm of rain falling," the Met Office said, adding that an amount of rain in such a short time - especially when the ground is hot - can lead to flash flooding.

The average rainfall for Hitchin during August is around 70mm.

The Met Office also explained the hot and muggy spell we've experienced in Hitchin since late last week were perfect for thunderstorms - adding: "Warnings have only been put in place because it was not yet possible to predict precisely where they would occur."

However, prior to the expected downpours, Hitchin would still face three days in a row of 35C temperatures – one of the longest times such heat has been recorded - with the ongoing heatwave set to break records.