It’s expected that today (September 9) could be the hottest day of the year so far with temperatures predicted to hit 33C in southern England.

The UK has seen five days of temperatures reaching above 30C already in September for the first time with the record likely to continue on Saturday and Sunday.

Provisionally, Thursday was the hottest day of the year with 32.6C recorded in Wisley, Surrey.

Saturday is to be hotter than Thursday though with areas around London predicted to bear the brunt of the hot weather.

The UK Health Security Agency has issued an amber heat health alert as a result.

The warning means weather impacts are likely to be felt across the health service with those aged above 65 or those with pre-existing respiratory or cardiovascular disease at greater risk.

In addition to the heat, the Met Office has also revealed Saturday brings the potential for thunderstorms across a large chunk of central Britain.

Large parts of the nation have been issued with a yellow weather warning for Saturday.

The Met’s yellow weather warning means some people could experience some flash flooding, lightning strikes, hail or strong winds with possible interruptions to road access and public transport if such circumstances occur.

What different Met Office weather warnings mean

Met Office chief meteorologist Paul Gundersen said: “Although much of the UK will see high temperatures and sunny skies continue on Saturday, in what has a possibility of being the hottest day of the year so far, there’s also the potential for some thunderstorms, which has resulted in a Yellow Warning being issued for much of central England and parts of east Wales.

“Temperatures will begin to trend downwards from Saturday in the far northwest of Scotland, with a cold front gradually moving south through the weekend, bringing with it the risk of some heavy and thundery downpours on Sunday as well.

“However, the southeast will hold on to the high temperatures the longest and could still reach 32C on Sunday.”

Environment Agency flood duty manager Chris Wilding warned motorists against driving through floodwaters in the case of flash flooding.

Ham & High: Motorists should avoid driving through floodwaters, says Environment Agency flood duty manager Chris WildingMotorists should avoid driving through floodwaters, says Environment Agency flood duty manager Chris Wilding (Image: Victoria Jones/PA)

Mr Wilding said: “Significant surface water flooding is possible but not expected across parts of England on Saturday afternoon and evening due to isolated intense downpours.

“We urge people not to drive through floodwater – it is often deeper than it looks and just 30cm of flowing water is enough to float your car.”

Mayor of London Sadiq Khan has issued a “high” air pollution alert for the capital for Saturday, the first since June, and urged Londoners to stop their engines idling and refrain from burning wood or garden waste.

But the UK is expected to return to cooler weather next week with a mix of sunshine, showers and some windy conditions likely as temperatures return towards the average for the time of year.