What is a heatwave? Weather event explained with one to arrive in the UK making it warmer than Barcelona

Heatwaves are becoming more common in the UK, with three last summer alone. Here we explain what a heatwave is, as one is reportedly on its way

A heatwave is reportedly set to descend on the UK this weekend, bringing blue skies, sunshine and sending temperatures soaring. Weather in some parts of the country is set to exceed the temperature in Barcelona, and match Madrid.

Last year was a record breaking one for weather in the UK. For the first time, temperatures exceeded 40°C. A highest maximum temperature was reached on July 19, 2022 with 40.3°C recorded at Coningsby, Lincolnshire.

During that scorching summer in 2022, the UK experienced three heatwaves; the first was for three days in June, the second for three days in July, and the third last for almost a week in August.

So, with a heatwave on the way soon, and temperatures set to rise above 20°C, here’s what a heatwave is, and how a period of weather is classified as one.

What is a heatwave?

According to the Met Office, “A heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity.”

A heatwave is achieved when a location “records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold”. However, the threshold varies by county in the UK.

Heatwaves occur when high pressure develops across an area. They happen in the UK due to the jet stream location which is usually to the north of the UK in the summer. Climate change also make heatwaves more likely.