Most Cities Are Getting Hotter. Not All Residents Feel It Equally

Some neighborhoods and communities can feel hotter than others in the same city on the same day. As cities adapt to extreme heat, understanding these disparities — and the solutions to mitigate them — is more essential than ever. 

On a hot day in February 2024, volunteers dispersed across Cape Town, South Africa, with sensors affixed to their cars. Their aim was to measure heat differences across the city. In Cape Town's dense, highly developed center, they recorded air temperatures as high as 41.6 degrees C (106.9 degrees F). Informal settlements like Joe Slovo, just north of the city center, were nearly as hot. Yet, leafier residential areas southeast of downtown barely broke 25 degrees C (77 degrees F).  

In the world’s largest capitals, the number of extremely hot days (above 35 degrees C, or 95 degrees F) per year has risen 25% since the 1990s. Within cities, heat is felt unevenly across communities — but some cities are finding ways to fix that.  

The Inequity of Heat

Urban residents who are already socially and economically vulnerable face the greatest risks from extreme urban heat, according to the Intergovernmental Panel on Climate Change. In Mumbai, where temperatures can surpass 38 degrees C (102 degrees F), the whole city can feel sweltering and all residents are at risk of heatstroke. But WRI India research has found that lower-income wards are hotter than wealthier areas and lack critical cooling resources like vegetation, magnifying already-hazardous conditions.

At the core of this disparity is the composition of the urban landscape. More well-resourced areas tend to have more vegetation, trees and buildings made of heat-resistant materials — all of which help protect residents from extreme temperatures. Lower-income areas and informal settlements, by contrast, often have less greenery and more buildings made of cheaper, heat-trapping materials like metal, making high temperatures even more unbearable.

But socioeconomic disparities explain only part of the variation in how people experience heat across a city. As in Cape Town, central districts with dense development and busy pedestrian corridors often lack the vegetation and shade needed to keep cool. In major tourist areas, like the President’s Mansion (Casa Rosada) in Buenos Aires or Mexico City’s Zócalo, people often gather in open, unsheltered plazas that trap heat, exposing large numbers of people to potentially dangerous temperatures. As more cities around the world commit to mitigating extreme heat — over 200 cities have joined the UN’s Beat the Heat initiative to accelerate local action — it’s vital that decision-makers recognize an important truth: While there is no one-size-fits-all solution for urban heat, there are cooling solutions that can work across a range of different cities and contexts.  

A good starting point is better data that shows just how widely heat hazards vary across cities, neighborhoods and even streets. WRI’s Cool Cities Lab data platform enables hyperlocal heat-risk analysis and scenario modeling of different cooling solutions. Here, we explore how three cities around the world experience heat inequity — and how they’re using locally appropriate solutions to alleviate it.

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