Citizen Scientists Across US Create Maps of Urban Hot Zones

On different days this summer, volunteers fanned out across more than a dozen US cities. With sensors hanging from their car windows — or, in the case of Brooklyn in New York City, attached to their bikes — nearly 800 people meandered along designated routes, measuring air temperatures and humidity levels while also collecting location data.

They were all taking part in the National Oceanic and Atmospheric Administration’s massive project to map the urban heat island effect, which causes urban air temperatures to be significantly higher than in nearby rural areas. The project has taken place in more than 60 cities since 2017, with each ...