Major Cities Worldwide Facing 25% Surge in Extreme Heat Days Since the 1990s
Capitals like Rome, Beijing, Madrid, and Manila hit by dramatic rise in days over 35°C—vulnerable communities bearing the brunt.
A new study by the International Institute for Environment and Development (IIED) shows that 43 major capitals around the world are experiencing 25% more days of extreme heat (above 35°C) compared to the early 1990s. The average number of such days rose from 1,062 per year (1994-2003) to 1,335 in 2015-2024. Cities such as Madrid, London, and Manila have seen striking increases.
Impacts and Risks
Vulnerable populations—informal settlements, the elderly, and those without access to cooling—are most at risk. Heat contributes to illness, reduced productivity, and increased mortality.
Urban heat islands (dense concrete, little green cover) amplify temperature, especially at night, making heat relief difficult.
Infrastructure (e.g. electricity, water, health systems) may struggle under recurring heat stress.
What Cities Are Doing / Can Do
Expanding green cover, rooftop gardens, shading, tree planting.
Improving building design for passive cooling, reflective surfaces, better insulation.
Heat-response plans: cooling centers, water access, early warnings.
Urban planning measures: more open water bodies, better airflow in city layouts.
The data is a wake-up call: heat is no longer just an occasional extreme—it’s becoming a norm in many big cities. Adaptation is no longer optional; it’s essential. Those who act early, and with equity in mind, will save lives.
