These city maps show how much hotter it is from neighborhood to neighborhood

Seeing how much hotter certain neighborhoods can get compared to others nearby blows my mind, and I report on this kind of thing for a living.

I live in New York City, which tops a new list of places in the US where temperature spikes because of urban sprawl. It’s a problem called the urban heat island effect. Basically, areas with more paved surfaces and less greenery trap heat. That raises temperatures in cities compared to more rural locations. It also makes certain neighborhoods within a city hotter than others.

A new analysis ranks 44 major cities that altogether are home to a quarter of the country’s population. More than half of the population in these cities live in census tracks that can feel at least 8 degrees Fahrenheit hotter than surrounding areas, according to the analysis published yesterday by the nonprofit Climate Central.

Temperatures from neighborhood to neighborhood are also mapped out in color-coded data visualizations from Climate Central. New York City, on average, feels about 9.5 degrees Fahrenheit warmer than surrounding areas. That number is its urban heat island index (UHI), a measure of the difference in temperature between an urban census tract and an area nearby that’s more rural.

But look closer, and you’ll see that some neighborhoods get much steamier than others. For example, it can feel up the 12.27 degrees hotter in Downtown Brooklyn.

Image: Climate Central

For a more interactive map, check out The City. Its map, based on Climate Central’s data, allows you to zoom in on an address to see how much hotter it is in that particular location. The Verge also mapped the most “heat-vulnerable” parts of the city, according to city officials, back in 2021. It’s an assessment of which residents are more at risk for heat-related death based on factors like local surface temperatures, access to air conditioning and cooler green spaces, income, and race.

Americans of color live in census tracts nearly 2 degrees Fahrenheit hotter, on average, in the summer than non-Hispanic white residents, a 2021 study found. Lower-income households also face disproportionate exposure to extreme heat, according to the EPA.

The Verge saw some of these disparities firsthand when we mapped New York. We hit the streets with a thermal camera to measure differences in surface temperatures between vibrant but heat-vulnerable East Harlem and less-vulnerable and more affluent Upper East Side. We found street surface temperatures more than 20 degrees hotter in East Harlem.

San Francisco ranks second on Climate Central’s list of cities, with its average urban heat island index per capita reaching 8.8 degrees Fahrenheit. While San Francisco has a reputation for being cooler than other parts of California because of its location on a peninsula, certain neighborhoods can feel much different than others. The city’s financial district can feel a whopping 12.64 degrees Fahrenheit hotter than nearby areas.

Image: Climate Central

Chicago and Miami are next on the list, with urban heat island indexes of 8.3 degrees Fahrenheit. You can see how more cities rank on Climate Central’s website.

Many of them are already working on ways to cool themselves down. The urban heat island effect is so prevalent because of decades of redlining that segregated neighborhoods and city planning that failed to address how the built infrastructure would make heatwaves feel even worse for its residents.

Concentrating industrial facilities and major roadways in certain areas, especially when people share fence lines with them, is a major problem. Smokestacks and tailpipes release heat along with pollution — which can burden nearby communities with disproportionate rates of lung disease that might also make heatwaves more dangerous for them. Paved surfaces also absorb heat during the day and then reemit it at night, extending the risks posed by a particularly hot day. Adding more trees and green space can significantly cool a neighborhood down. So can painting rooftops white to reflect sunlight.

Image: Climate Central

Image: Climate Central

Summer heat is getting more intense with climate change, so cities will have to adapt. Extreme heatwaves that hit North America this month would have been “virtually impossible” without climate change, a study by an international collaboration of researchers recently found. And July is on track to be the hottest month on record, the World Meteorological Organization said today.