The first year of the Weather Health Alert (WHA) system – jointly run by the UK Health Security Agency (UKHSA) and the Met Office – coincided with more than 1,300 deaths during four heatwaves in the summer of 2024 and over 5,500 deaths linked to cold weather in winter 2022/23, official figures show.
A review carried out by Surrey’s Institute for Sustainability found that the new system is proving useful for emergency planners, local authorities, healthcare providers and others supporting vulnerable groups. The evaluation, undertaken through the Institute’s Sustainability Innovation Hub consultancy, assessed stakeholder experiences with the WHA system in its first year.
The system uses colour coding – yellow, amber and red – alongside numerical risk scores to reflect both the likelihood and potential impact of weather conditions. Yellow typically signals impacts on vulnerable groups or local services, amber represents more serious and widespread impacts requiring coordinated responses, and red is reserved for extreme events where urgent action is needed.
Published in the journal Environmental Science and Policy, the review drew on workshops with 93 participants including emergency planners from local authorities, the NHS, central government and frontline service providers, followed by in-depth interviews.
Dr Thomas Roberts, Co-Director of the Institute for Sustainability, said: “At the end of the UK’s hottest summer on record, featuring four heatwaves, it is clear that tools to protect vulnerable people from weather-related harm are now a critical part of our health and care infrastructure. Extreme weather is now the norm, and so swift and effective warnings are essential for protecting the population.”
The study highlighted positive outcomes such as fewer unnecessary alerts, reduced alert fatigue and better coordination between agencies. However, stakeholders reported difficulties distinguishing between the levels within the yellow alert band and noted that some frontline staff found the text too complex for rapid use. Participants suggested simplified summaries for quick reference, supported by detailed guidance for planners.
Dr Ross Thompson, Principal Environmental Public Health Scientist at UKHSA, said: “Our weather health-alerting system is designed to help stakeholders across health, care and voluntary sectors prepare for adverse temperatures that affect the population. We are pleased the findings show it is fulfilling its aim so early after launch, and we will continue to refine it with the Met Office.”
Haeyoung Eun, co-author of the study, added: “For frontline staff and the general population, the new system should mean better planning for heatwaves, safer care during cold spells and fewer shocks when extreme weather hits. If remaining sources of confusion are addressed, the WHA system could reduce health impacts even further in summers and winters to come.”
The project supports the UN Sustainable Development Goals on good health and wellbeing (SDG3), resilient infrastructure (SDG9), sustainable cities and communities (SDG11) and climate action (SDG13).
