A new report by the World Meteorological Organization (WMO) has said that according to modelled estimates, between 2000 and 2019, approximately 489,000 heat-related deaths occurred each year, with 45% of these in Asia and 36% in Europe.
The new report Extreme heat impacts millions of people published in August 2025 reveals that the extreme heat - with dangerously high daytime and overnight temperatures is impacting millions of people around the world, underlining the importance of early warnings and heat-health action plans. It said wildfires and poor air quality are compounding the problem.
WMO and its members are therefore committed to bolster heat early warning systems in line with the Early Warnings for All initiative and are working with partners at international, national and community level to strengthen heat-health action plans.
WMO Deputy Secretary-General Ko Barrett said, “Extreme heat is sometimes called the silent killer, but with today’s science, data and technologies, silence is no longer an excuse. Every single death from extreme heat is preventable.”
In cities, the impact of heat on human health is more pronounced due to the urban heat island effect. Elderly people and those with chronic illness are at higher risk.
According to the EU-funded Copernicus Climate Change Service, July 2025 was the third-warmest July globally (after July 2023 and July 2024). The average sea surface temperature was also the third highest on record. Arctic sea ice extent ranked joint second-lowest for July in the 47-year satellite record, virtually tied with 2012 and 2021.