30 June 2025

Parts of Europe have recorded unparalleled highs in temperature—over 46 °C in Portugal and Spain, with many regions hitting 42–43 °C this week. Europe is the fastest-warming continent. Since 2000, June heatwaves have surged—Spain saw nine such events after just two between 1975 and 2000.  Heat-related mortality in Europe has risen around 30% over two decades, with summer 2022 alone claiming 68,000 lives.  The urgency of this heat–health crisis has prompted calls for action from the highest levels, from the WHO Regional Director for Europe declaring the climate crisis and extreme weather a public health emergency in 2023 to the United Nations Secretary-General’s “Call to action on extreme heat” in 2024, both emphasizing the need for robust strategies to protect vulnerable populations.

Who's most at risk?

The human body has a remarkable capacity for thermoregulation, designed to maintain a core temperature of around 37 °C. When external temperatures rise, the body sweats to cool itself through evaporation. However, prolonged exposure to extreme heat causes suffering, impacting mental health and well-being, and eventually it may overwhelm this natural cooling mechanism, leading to serious health issues and potential medical emergencies.

Although everyone may be affected by the heat to some extent, the impact of extreme heat is not uniform: certain populations bear a disproportionate burden. Older adults have a reduced ability to sweat and regulate body temperature, and infants and young children have underdeveloped thermoregulatory systems. Outdoor workers, such as in agriculture, construction and emergency services, for example firefighters, face prolonged heat exposure as a potential occupational hazard.

Beyond direct heat-related illnesses, extreme temperatures exacerbate existing chronic conditions. Individuals with cardiovascular diseases, respiratory illnesses and diabetes are particularly vulnerable, as well as those taking certain medications. Pregnant women are also at higher risk, with extreme heat linked to adverse pregnancy outcomes such as preterm birth and low birth weight.

Why #KeepCool matters

Addressing these concerns, WHO/Europe’s annual #KeepCool campaign provides simple and practical guidance for individuals and communities to stay safe during hot weather. The adverse health effects of hot weather are largely preventable through good public health practice and simple yet highly effective steps that can be taken at the individual and community level.

Keep out of the heat. Avoid going out and doing strenuous activities during the hottest time of day. If you are vulnerable to heat, take advantage of opportunities such as special shopping times for older people in the cooler mornings and evenings. Stay in the shade, do not leave children or animals in parked vehicles and, if necessary and possible, spend 2–3 hours of the day in a cool place.

Keep your home cool. Use the night air to cool down your home. Reduce the heat load inside the apartment or house during the day by using blinds or shutters and turning off as many electrical devices as possible.

Keep your body cool and hydrated. Use light and loose-fitting clothing and light bed linen, take cool showers or baths, and drink water regularly while avoiding sugary, alcoholic or caffeinated drinks.

Keep in touch. Check on family, friends and neighbours who spend much of their time alone. Vulnerable people might need assistance on hot days. If anyone you know is at risk, help them to get advice and support.

These steps can drastically lower heat-related illness and mortality.

Beyond individual actions: systemic resilience needed

Beyond individual actions, a more comprehensive and systemic approach is vital. WHO/Europe recommends countries, regions and cities in the Region to develop and implement heat–health action plans, to prevent and respond to heat-related risks to health.

The process of heat–health action planning brings together actors from multiple sectors with the aim of better managing heat risks. These plans outline roles and responsibilities during extreme heat events, integrate early warning systems, identify vulnerable populations, and establish communication and response mechanisms. WHO/Europe is currently updating their heat–health action plan guidance to further support Member States in this process.

Summer heat is no longer just an exceptional seasonal phenomenon; it is a critical public health issue amplified by climate change. WHO/Europe’s #KeepCool campaign serves as a reminder that proactive measures, both individual and collective, are essential to safeguard health and well-being in an increasingly warmer world. By understanding the risks, changing our behaviour and looking out for each other, we can both support our health systems and ensure that summer remains a season of enjoyment, not a period of peril.

Climate change: the driving force

Record-breaking early heatwaves—now hitting in June—are a direct outcome of human-driven climate change. And Europe's warming trend threatens agriculture, biodiversity, and glacier stability—highlighting an urgent need for climate adaptation and mitigation measures.