The new warning, which was launched in June, acknowledges the adverse impacts of high temperatures on people’s health and on infrastructure, such as the transport and energy sectors.
It also notes that prolonged periods of unusually hot weather in the UK are more likely due to the effects of climate change.
Amber and red warnings can now be issued to inform the public of the possibility of widespread disruption and adverse health effects from extreme heat.
“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 in June.
“The extreme heat warningâ¯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, butâ¯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.