UK heatwave: What is a red weather warning for extreme heat?

A red heat warning has been issued for the first time. Credit: PA Images

A rare red warning is in place when dangerous weather is expected - in this case, extreme heat.

Weather warnings are issued by the Met Office when severe weather has the potential to affect parts of, or the whole of, the UK.

The extreme heat weather warning system ranges from amber to red and indicates how much of an impact the weather will have on public life.

What does a red weather warning mean and what are the risks?

A red weather warning is the most serious and means it is "very likely" that there will be a risk to life.

The Met Office advises: "Dangerous weather is expected and, if you haven’t already done so, you should take action now to keep yourself and others safe from the impact of the severe weather."

In its heatwave plan, the UK Government says a national emergency may be declared "when a heatwave is so severe and/or prolonged that its effects extend outside the health and social care system."

Health services are put under extra pressure during hot weather spells. Credit: PA Images

Extreme temperatures can cause health problems across the population, leading to potentially serious illness or danger to life.

Older people - especially those over 75 - young children, and those with pre-existing health conditions are particularly at risk.

But during a red warning for extreme heat, everyone has the potential for their health to be adversely affected - not just those most vulnerable, the Met Office says.

It adds: "Hot weather places a strain on the heart and lungs. For that reason, the majority of serious illness and deaths caused by heat are respiratory or cardiovascular."

When the weather is hot, significantly more people are likely to visit coastal areas, lakes and rivers - increasing the risk of water safety incidents.

All of this in turn will have an impact on emergency services across the country - particularly fire and health departments.

A train passes through heat haze as people are warned not to travel unless necessary. Credit: PA Images

There is also likely to be disruption to travel, with "significant" welfare issues for those who experience even moderate delays, the Met Office says.

Issues could include delays or cancellations to rail and air travel, while roads exposed to prolonged direct sunshine can melt in the heat, leading to closures.

Finally, it is highly likely that some essential services will be impacted, such as water, electricity, gas or mobile phone services, due to the high temperatures. This is also the case with heat-sensitive systems and equipment.

Has a red heat weather warning been issued before?

Red weather warnings in general are uncommon, with the Met Office saying it "rarely" issues one.

Weather warnings can be issued at any time for rain, thunderstorms, wind, snow, lightning, ice, extreme heat and fog, up to seven days ahead. Yellow warnings are more common than amber or red.

This is the first time a red warning for extreme heat has been issued in the UK since this particular type of alert was introduced in 2021.

In July of that year, the Met Office issued its first ever extreme heat warning - and that was amber.

The NHS recommends drinking plenty of fluids and avoiding alcohol. Credit: PA Images

What should people do when a red heat warning is in place?

If you or someone else feels unwell with a high temperature during hot weather, it may be heat exhaustion or heatstroke.

Government advice is that 999 services should be used in emergencies only. Seek advice from 111 if you need non-emergency health advice.

Changes to working practices and daily routines will be needed to help protect people during a red heat warning.

The NHS website reminds the public that it is important to stay hydrated and to stay in the shade where possible between 11am and 3pm, when UV rays are strongest. Protect yourself by applying sunscreen every two hours.

Check on those most vulnerable to extreme heat, including older people, children, and those with health conditions, and also make sure animals - particularly those outdoors - are protected.

The Met Office says people should avoid travelling where possible, but when unavoidable it is important to ensure you are prepared by checking the latest travel information.

The AA Driving School and RAC advises motorists to carry water with them, start their journeys earlier in the day, plan their routes and check their vehicles before setting off on any journeys.

What is the hottest day ever recorded in the UK?

The UK record of 38.7°C was set at Cambridge Botanic Garden on 25 July 2019.