Although hot weather can often be seen as ‘good news’ and is enjoyed by many, it can have serious consequences. Research shows that, as a result of climate change, we are now much more likely to see prolonged spells of hot weather here in the UK.

The impacts of extreme heat can be many and varied. It can have health consequences, especially for those who are particularly vulnerable, and it can impact infrastructure, including transport and energy, as well as the wider business community. During hot weather we often see increased traffic near coastal areas, increased use of open water by the public, and an increase in wildfire risk.

The Met Office launched a new Extreme Heat National Severe Weather Warning at the start of June 2021, with warnings to be issued based on the impacts of extreme heat.  Amber and red warnings can now be issued to inform the public of potential widespread disruption and adverse health effects.

Amber and red extreme heat warnings are now available to be issued by the Met Office (Image: Shutterstock)

A changing climate

The impacts from extreme heat are increasing across the UK due to climate change. The UK State of the Climate report shows that warm spells have more than doubled in length (from 5.3 days in 1961-90 to over 13 days in 2008-2017). In addition, extreme summer temperatures like those seen in 2018 are now 30x more likely than in pre-industrial times. The latest Met Office projections of future UK climate change also suggest that these summer temperatures could be ‘normal’ by the 2050s.

Dr Will Lang, Head of Civil Contingencies at the Met Office, said, “We know that the impacts of climate change are resulting in an increase in the frequency and severity of extreme heat events. 

“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. 

“Extreme heat has obvious potential consequences 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.”

Working with others

The Met Office has been working closely with Public Health England, the devolved administrations and other key stakeholders to develop the UK-wide extreme heat warning.

Extreme heat warnings will work in a similar way to the existing weather warnings, where they’re only issued based on the impacts of the weather conditions, rather than when specific temperatures are reached. This means that different conditions in different areas of the country may trigger an extreme heat warning, and the threshold for an extreme heat warning in Aberdeen, for example, is likely to be lower than one covering London.

In the most extreme circumstances, prolonged spells of heat can cause illness and even death. According to Public Health England figures, 2,256 excess deaths were reported across the country during heatwaves in the summer of 2020 – the highest since records began. It’s hoped the new extreme heat warning can help the public, businesses and organisations better prepare for hot conditions, thereby reducing disruption and impacts.

Find out more about the Met Office’s weather warnings.

An extreme heat warning is different than the Met Office’s definition for heatwaves. Find out about when heatwaves are declared.