Hot weather is a 'silent killer': Expert comment on Red Weather Health Alerts

What does a Red Weather Health Alert actually mean and how does it differ from lower-level alerts?

"A Red Weather Health Alert is the highest level of warning and means severe weather is expected to have widespread impacts on public health, health and social care services, and critical infrastructure. Unlike Yellow and Amber alerts, which focus on preparedness and increasing levels of risk, a Red alert indicates that immediate action is needed.

"Importantly, these alerts are not based solely on temperature. They also consider factors such as humidity, warm nights, the duration of the event and pressures on services, providing a much clearer picture of the likely impacts."

Britain has no legal maximum workplace temperature. Is that still fit for purpose in an era of Red Weather Health Alerts?

"As extreme heat becomes more frequent, it raises important questions about whether current approaches remain appropriate. While there is no legal maximum workplace temperature, employers already have a duty to assess and manage risks to staff.

"Organisations will increasingly need to prioritise heat resilience through measures such as better ventilation, access to hydration, flexible working arrangements and additional protections for those most at risk. Climate adaptation is no longer something we need to prepare for in the future. It is something we need to be doing now."

Are there any common misconceptions about heat alerts?

"One of the biggest misconceptions is that only exceptionally high temperatures are dangerous. In reality, health impacts are influenced by a combination of factors including humidity, warm overnight temperatures, the duration of the heatwave and who is exposed.

"There is also a tendency to think heat only affects older people. While they remain particularly vulnerable, prolonged heat can also affect people with underlying health conditions, outdoor workers, young children and the ability of health and social care services to operate effectively."

Why does heat kill more people in the UK than many people realise?

"Heat is often described as a silent killer because it rarely causes dramatic, immediate deaths. Instead, it worsens existing cardiovascular, respiratory and kidney conditions over several days, leading to increased hospital admissions and excess mortality that may not be recognised as heat-related.

"The UK is also relatively poorly adapted to prolonged heat, with many homes, workplaces and hospitals designed to retain warmth rather than lose it."

What should the public do differently when they see a Red Weather Health Alert compared with a standard hot weather forecast?

"A Red Weather Health Alert should be treated as a public health warning rather than simply a weather forecast. People should take practical steps to protect themselves and others, including checking on vulnerable relatives and neighbours, avoiding strenuous activity during the hottest part of the day, staying hydrated and keeping homes as cool as possible.

"While Red alerts attract the most attention, Yellow and Amber alerts are equally important because they provide valuable time to prepare. As climate change makes extreme heat more common, successful adaptation will increasingly depend on acting early rather than waiting until the highest level of alert is reached."