Flash floods and thunderstorms to hit UK with possible power cuts and travel chaos as heatwave ends

Flash floods and thunderstorms will hit parts of the UK over the coming days with high temperatures giving way to breezier conditions by the end of the week.

Forecasters have said fresher conditions are expected from late Wednesday (17 August), following the scorching temperatures that hit the majority of the country over the weekend.

The Met Office issued an amber thunderstorm warning for areas of Cornwall, Devon and Somerset, with the likely chance of homes and businesses flooding, power cuts, and transport chaos.

Yellow warnings are also in place for most of the UK on Tuesday (16 August) and for southern England on Wednesday.

What is the forecast for the rest of the week?

Hail, frequent lightning and flash flooding is possible in areas further south, with heavy rain predicted across England and Wales on Tuesday (16 August). The rain is likely to become more concentrated in southern parts of England.

Downpours are expected across Scotland on Tuesday but will gradually clear as the day goes on, while Northern Ireland will be the driest.

Tuesday is expected to be “rather cloudy with some patchy light rain” that would gradually clear in Northern Ireland.

Meanwhile the forecast for Wednesday is mainly dry with a prolonged bright and sunny period.

Met Office meteorologist Greg Dewhurst said: “Temperatures will be lower, looking at highs of around 27C as a maximum temperature, but it will still be on the humid side tomorrow (on Tuesday).

“Thundery showers across central and southern parts of England on Wednesday and temperatures will be around 26C as a maximum.”

Which areas have been affected by flooding?

Heavy showers caused flooding in areas of Cornwall and Devon on Monday afternoon while thunderstorms developed in east-coast counties like Essex, Suffolk and Lincolnshire.

Footage shared to social media showed a roundabout near the river in Truro, Cornwall quickly flooding with water on Monday afternoon as showers moved in.

Heavy downpours and flooding have also hit parts of Ireland as thunderstorms marked the end of the heatwave.

In Northern Ireland, thunderstorms on Sunday (14 August) caused the Met Office to issue an amber weather alert warning of hail, lightning and potential flooding - which came to an end on Sunday night.

Mr Dewhurst warned that the bad weather conditions could pose difficulties for those hoping to travel and urged people to stay up to date with developments in their local area.

He said: “We’ll see some very heavy showers develop over the coming days, hail, frequent lightning, some flash flooding is possible like we’ve seen in places today so our advice is to stay tuned to latest forecasts and local radio stations as well, to get the latest information.

“It is worth being aware that there could be disruptions or delays to travel.

“It will be in turns fairly breezy as we end the week, with some showery rain, particularly across the north of the UK, so temperatures generally around average for many but could possibly be a bit above for the far south, which is the mid-20s.

“It looks probably most likely from late Wednesday to Thursday onwards it will become fresher for everyone.”

Why is there a risk of flooding?

Professor Hannah Cloke, an expert in hydrology at the University of Reading, explained why there is the potential for floods in drought-hit areas.

She said: “The ground is really dry and when it is so dry it acts a little bit like concrete and that water can’t get in so it drains straight off.

“There is the damage to homes and businesses these floods can cause, and inconvenience with transport disruptions, but if it is very heavy in one place it can also be very dangerous.”

Explaining why this heavy rain will not alleviate drought-hit areas, she said: “It’s a drop in the ocean really. It is not soaking into the soil which is how we really need it.

“We need it back into the system where it can be stored. We really need a long winter of rain to replenish this.”