The Met Office has issued a serious amber weather warning for extreme heat from Monday in 51 UK areas - and has warned the hot weather could bring power cuts.

The weather experts have warned that ‘extreme heat’ will affect mostly the south of England and Wales from 1am on Monday, lasting 46 hours until 11.59pm on Tuesday night.

The heat will bring ‘mid-30s’ temperatures in Celsius and even 20C overnight, the Met Office said.

It warned that the hot weather could even cause ‘heat sensitive systems and equipment’ to fail, leading to ‘power cuts and the loss of other services to homes and businesses’.

It said: “A developing hot spell is expected to peak on Monday and Tuesday and lead to widespread impacts on people and infrastructure.

“Following very warm weather on Sunday, very high temperatures are expected on Monday and Tuesday and will likely bring widespread impacts to people and infrastructure. In addition to high daytime maxima, temperatures overnight will remain very warm, especially in larger urban areas, and it will also feel humid.

“Temperatures are likely to reach the mid-30s Celsius in places on Monday and Tuesday. Some places, particularly in urban areas, may see temperatures remain above 20 Celsius overnight.

“The very high temperatures may continue across a smaller area into the middle of the week, but there remains some uncertainty regarding the extent of this.”

In its advice, the Met Office added: “Keep yourself safe whilst enjoying the water in this weather by following these simple steps: enter the water gradually, avoiding jumping or diving straight in, to reduce your risk of cold-water shock, go to a lifeguarded beach or a supervised swimming area, and, if you, or anyone else, get into difficulty in the water, float on your back.

“People cope better with power cuts when they have prepared for them in advance. It’s easy to do; consider gathering torches and batteries, a mobile phone power pack and other essential items.”

The full list of areas affected by the amber heat warning are: