UK heatwave: When will the heatwave end? How hot will it get? Will temperatures reach 40°C?

The Met Office has forecast that the mercury will reach highs of 29°C in Sussex on Tuesday (July 12), with hot temperatures forecast across the UK for the rest of the week.

And next week is predicted to be even hotter, with the Met Office forecasting temperatures of up to 35°C next Monday (July 18).

The Met Office, along with the UK Health Security, has issued a Level 3 Heat Health Alert, with experts warning those in the South East of England to keep safe over the coming days.

The Met Office has warned of a possibility that temperatures in Britain may reach 40°C by mid-July.

Here’s everything you need to know about the heatwave.

How long will the UK heatwave last?

In a statement released by the Met Office on Thursday, July 7, meteorologist David Oliver laid out the potential weather patterns.

He said: “We’re at the start of a stretch of warm weather for much of England and Wales, that could last for much of next week.

“In the short term, many can expect temperatures in the mid to high 20s Celsius over the weekend, and then in the low 30s Celsius during the start of next week.

“Much of next week will remain warm for the time of year as well as dry and sunny.”

Greg Dewhurst, also from the Met Office, added: “For most of us it will be a dry and sunny day, well into the high 20s from the morning, with central, southern and eastern parts of England to possibly see maximum highs of 33C.

“So it’s very possible tomorrow will be the hottest day of the year so far, it will certainly be on par with the existing record, maybe more.

“It will also be very warm overnight going into Tuesday, remaining in the low 20s in cities, so many may experience an uncomfortable night.”

Speaking on the latest Met Office 10 Day Trend, meteorologist and presenter Alex Deakin said: “There's good model certainty that we’ll see a peak in temperatures in the early part of next week but there’s one possible scenario where temperatures get even higher late next week.

“A more likely scenario is that temperatures return to something similar to Monday and Tuesday and there’s also a chance temperatures could drop much closer to average.”

Deputy chief meteorologist David Oliver added: “There are some runs, or solutions, that allow more extreme temperatures to develop into next weekend, which is something we will be monitoring closely over the coming days and adding more detail around into the new week.”

How hot will it get in the UK?

The Level 3 Heat Health Alert states that the South East is likely to see temperatures in the low 30s.

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In their statement, the Met Office warned of “likely adverse health effects for the public, not just limited to those most vulnerable to extreme heat. Temperatures could be in excess of 35C in the southeast, and more widely around 32C within the warning area.”

“These high temperatures could extend into the early part of next week and an extension of the warning will be considered in the coming days.”

A second Met Office spokesperson said: "There is increased confidence that temperatures will rise through the weekend, becoming widely hot, locally very hot from Monday next week.

"The highest confidence is for southeastern and eastern areas where temperatures are expected to reach the low 30s. Temperatures are likely to stay close to threshold through Wednesday, especially in for southern areas."

But, speaking to The Sun, Met Office forecaster Steven Keates warned temperatures could peak at a sweltering 43°C

He said: “Next weekend we could have some really exceptional record-breaking heat and it will ramp up suddenly — like someone has turned on the gas.

“Some models from America indicate we could see 43°C in East Anglia next Sunday, which would obliterate the current UK record.”

Will UK temperatures reach 40°C?

The risk of 40°C temperatures in the UK is particularly high at the moment – the highest its ever been. However, there are a number of different things that would have to happen for the UK to reach 40°C, and it’s unlikely that each of those factors would align perfectly.

For the UK to reach 40°C in July, the warmest air from Africa would need to move through Spain and France to the UK. This would depend on low air pressure in and around Iberia.

Nonetheless, even if temperatures don’t reach 40°C, the Met Office has still warned that there is a “30% risk” of a new record temperature being set. The current record is 38.7°C in July 2019.

Matthew Killick, director of crisis response and community resilience, British Red Cross, said: “We’re all looking forward to enjoying some warm weather this summer, but it’s important to remember that heat can be very dangerous, especially for children, older people and those with underlying health conditions.

“Climate change means we’re experiencing longer and more intense heatwaves, but a worrying number of people aren’t aware of the risks around hot weather.

“In England alone there were more than 2,500 excess deaths in the summer of 2020, and unfortunately it’s predicted that heat-related deaths in the UK could treble within 30 years.”