These are the 5 US cities with the most people living in urban heat islands

Name: Preventing heat exhaustion and heat stroke
Uploaded: 2023-06-20T14:38:25-04:00
Duration: 4 min 22 s
Description: Dr. Richard Bradley, an emergency medical services physician, discusses best practices to prevent heat exhaustion and heat stroke.

Dr. Richard Bradley, an emergency medical services physician, discusses best practices to prevent heat exhaustion and heat stroke.

04:22

Preventing heat exhaustion and heat stroke

Dr. Richard Bradley, an emergency medical services physician, discusses best practices to prevent heat exhaustion and heat stroke.

An estimated 41 million people in major U.S. cities experience temperatures that are at least 8 degrees warmer than those felt by people living outside the cities.

The climate communications group Climate Central studied 44 major cities across the country, ranging in size from Wichita, Kansas, with a population of about 554,000, to New York City, with a population of more than 9 million. The group also refined their research within the cities by using census tracts to zoom in and learn about populations within specific districts.

For each of the cities, researchers calculated an urban heat island (UHI) index, which measures the difference in temperature between urban areas and rural areas. Because many urban areas are warmer than the surrounding rural areas, they are often referred to as "urban heat islands."

WHAT IS AN URBAN HEAT ISLAND?

A graphic showing the temperature differences between rural, industrial, urban, park and suburban areas.

(Climate Central / FOX Weather)

Key factors contributing to the creation of urban heat islands include miles of hard and dark surfaces, population density, less vegetation and buildings that impact airflow in cities, according to Climate Central.

The group found that of the 74 million people within the study’s analysis, about 55%, or 41 million, lived in areas with a UHI index of 8 degrees or higher. This means that when the temperature in a rural area outside a city is 90 degrees, it is closer to 98 degrees or higher for many people in the city.

Here are the five cities with the highest UHI indices, according to their study.

1. New York City

The most populous city in the country, New York City, has the highest number of residents living with a UHI index of 8 degrees or higher. About 78% of the population, or more than 7 million people, are affected.

Helicopters fly in the distance as the sun sets behind the Statue of Liberty in New York on Nov. 3, 2022.

(ANGELA WEISS / AFP / Getty Images)

2. Houston

The fourth-largest city in the nation and the largest city in Texas, Houston has an estimated 4.2 million people living in an area with a UHI index of 8 degrees or higher. This translates to about 73% of the total population of Houston.

This photo taken on June 21, 2023 shows a temperature display reading 99 degrees Fahrenheit about 37.2 degrees Celsius in late afternoon in Houston, Texas, the United States. An "oppressive" heat wave is continuing scorching the south central U.S. state of Texas, where triple digit temperatures are expected to last for the next several days, forecasters said on Wednesday. (Photo by Chen Chen/Xinhua via Getty Images)

A temperature display reading 99 degrees Fahrenheit in Houston, Texas. June 21, 2023.

(Chen Chen / Xinhua / Getty Images)

3. Los Angeles

The largest city in California and the second-largest city in the country, Los Angeles has about 3.2 million people living in an area with a UHI index of 8 degrees or higher. This translates to about 45% of the total population of Los Angeles.

PACOIMA, CA - AUGUST 3, 2021 - - Felisa Benitez, 86, wipes the sweat from her brow while taking a break from cleaning her stand-up electrical fan on the porch of her home where temperatures reached 99 degrees at the San Fernando Gardens Public Housing in Pacoima on August 4, 2021. Benitez, who lives alone, tries to only use fan to cool herself even though she has an AC unit, to the right, at her place. She is on a limited budget and uses the AC sparingly to avoid a huge electrical bill that she cannot afford to pay. Benitez, who has lived at the gardens since the 90s, spends a great deal of her day seated in the shade of her porch. According to Los Angeles County Coroners and Medical Offices, hundreds of heat-related deaths reviewed by the Times showed the victims included seniors who died alone in apartments without air conditions, or with the thermostat off. (Genaro Molina / Los Angeles Times via Getty Images)

FILE - An elderly woman wipes the sweat from her brow.

(Genaro Molina / Los Angeles Times / Getty Images)

4. Dallas

Back in Texas, Dallas has nearly 2.2 million people living in an area with a UHI index of 8 degrees or higher. This translates to about 75% of the city’s total population.

A monitor reads the current temperature as 100 degrees Fahrenheit outside a building during a heatwave in Dallas, Texas, US, on Tuesday, June 21, 2022.

(Shelby Tauber / Bloomberg / Getty Images)

5. Chicago

The largest city in Illinois has more than 2 million people living in an area with a UHI index of 8 degrees or higher. This translates to about 52% of the city’s total population.

A man is seen with his shirt sweaty in downtown Chicago, the United States, on June 14, 2022. The Chicago metropolitan area is bracing for a heat wave, as the U.S. National Weather Service issued a heat advisory for the area on Monday.

(Vincent D. Johnson / Xinhua / Getty Images)

At the bottom of the list was Wichita, which has an average UHI index per capita of 7.2 degrees.

To view the full list of cities that were part of this study, check out this document by Climate Central.

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