Extreme heat warning: What is the Met Office amber alert?

Forecasters say climate change is making extreme heat events more frequent and severe

The Met Office has issued its latest weather warning for extreme heat in the UK after a weekend that brought scorching temperatures across all four nations.

The warning was issued for Sunday 17 July and covers most of England and much of Wales, with temperatures forecast to hit 35C in the south east.

Amber and red warnings were first introduced in June 2021 to acknowledge the adverse impact of extreme conditions on people’s health and the possibility of widespread disruption being caused to certain industries, notably the transport and energy sectors.

In launching the system, the Met Office acknowledged that prolonged periods of unusually hot weather in the UK are more likely due to the effects of climate change.

“We know that the impacts of climate change are resulting in an increase in the frequency and severity of extreme heat events,” Dr Will Lang, head of civil contingencies at the Met Office, said last summer.

“The extreme heat warning joins our other warnings to ensure that no matter what the weather conditions, we at the Met Office have a method of communicating these impacts to the public in as efficient a way as possible.”

He added: “Extreme heat has obvious potential consequences to health in the UK, especially for vulnerable groups, but continued impacts around transport infrastructure, energy consumption and coastal areas will also inform when extreme heat warnings are issued.”

The Met Office has also noted that an extreme heat warning is only issued based on the impact of the weather conditions, rather than specific temperatures being reached.

For example, this means that the threshold for a warning in Aberdeen in Scotland is likely to be lower than one for London, where high temperatures are more common.

What to expect when an extreme heat warning has been issued

The Met Office has warned that periods of extreme heat are likely to cause adverse health effects for those who are vulnerable to high temperatures, such as older people or people with underlying conditions.

However, other people may also experience adverse health effects like sunburn or heat exhaustion, with symptoms such as dehydration and fatigue.

In addition, some heat-sensitive systems and equipment may fail, leading to power cuts or loss of services at some homes and businesses, while delays to road, rail and air travel are also possible.

The weather service also suggests that “some changes in working practices and daily routines are likely to be required” due to the effects of extreme heat.