As cities sizzle, mapping projects pinpoint the perils of hot neighborhoods

Intrepid street vendor Lauro Ilario drives a golf cart across the Phoenix asphalt for several hours a day selling cold drinks, snow cones and snacks to people he finds walking the streets.

But Phoenix just suffered through the hottest month ever recorded in an American city — and hardly anyone walks the street when it's 110 degrees outside. During the heat wave, Ilario says his sales fell to just $50 dollars when normally he'd make three times that. That's thousands of dollars of lost revenue at a time when electric bills are soaring.

Long before this heat descended on the state and made life miserable for people like Ilario, researchers began looking for ways to protect American cities from extreme temperatures. But first, they have to know exactly how hot it is. This summer the National Oceanic and Atmospheric Administration recruited citizen scientists in 14 states to help measure just how hot it’s getting. The data could help city officials and community groups address extreme heat in the neighborhoods that need it most.