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What is a heat dome? Temperatures to reach 28°C in the UK

People enjoy the hot weather on Bournemouth beach  (Andrew Matthews / PA)
People enjoy the hot weather on Bournemouth beach (Andrew Matthews / PA)

This week is seeing record high temperatures across much of the world, with heatwave warnings in the US, Europe, and other regions.

Greece, Cyprus, and Turkey are among the European locations experiencing intense heatwaves above 40°C, leading to wildfires, evacuations, and fatalities.

This week’s US heatwaves have been attributed to a heat dome and it may be coming to the UK.

While there are no heatwave warnings for the country, Dan Harris, the deputy chief meteorologist at the Met Office, predicted earlier this week that temperatures in the UK would see a "steady uptick" in the next several days.

Temperatures for London show an increase in temperatures from Friday, June 21 to Wednesday, June 25, ranging from 24°C to 28°C.

“In stark contrast to the first half of June, where temperatures have widely been below average, we are expecting to see a steady uptick through the second half of this week, rising to around or above average, and it will likely feel very warm for those in the sunshine.

“This initial spell of warm conditions isn’t expected to last too long, however, as it turns more changeable through Friday (June 21) and into the weekend with areas of cloud and rain spilling east across the UK.”

What is a heat dome?

The Royal Meteorological Society says a heat dome takes place when an area of high pressure stays over the same area for days (sometimes weeks). Warm air then gets trapped underneath like a lid on a saucepan, pushing temperatures above what is normal for the time of year.

The heated air expands upwards into the atmosphere, then high pressure from above acts as a barrier, meaning it can't escape and causes the air to subside or sink. This creates a dome effect.

The warm air sinks and compresses and heats up, which then traps more heat underneath. Clouds are pushed around it, trapping the heat even more.

However, meteorologist Dr Chris England told Sky weather that the phenomenon “doesn't really apply to the current heat of the UK”, and that the flow around the high pressure comes from the south over the UK, bringing heat up from the Mediterranean and north Africa.

Is heat dome a new term?

The term first came into general use in 2011.

Oklahoma City weatherman Gary England told the New York Times: “I’ve used ‘heat dome’ off and on over the years, but I think it’s a little bit misleading; it’s not shaped like that.”

What is the difference between a heat dome and heat wave?

The terms “heat domes” and “heat waves” are often used interchangeably but heat domes are just one of the atmospheric conditions that can contribute to the formation of a heat wave.

A heat wave is a period of excessively hot weather for a prolonged period of time, often with high humidity.