This story appears in the August 2019 issue of National Geographic magazine.
Thermometer-wielding volunteer drivers are partnering with climate researchers to create maps of urban heat islands across the United States. On a hot day in Washington, D.C., for example, temperatures varied nearly 17 degrees F between the warmest spot and the coolest. To cope with the heat, many cities are planting trees and carving out open spaces. The National Oceanic and Atmospheric Administration, which funded the research, plans to expand it to help cities figure out ways to keep their cool in a warming world.
