That will be true for many more cities as the world gets hotter
Photographs by George Etheredge | Written by Marguerite Holloway | The New York Times
Dozens of hikers set out for the summit of Piestewa Peak on a July evening, their flashlights dancing in the dark. “You feeling O.K.?” Trevor Plautz, a park ranger, asked two women, one of whom had stumbled and was breathing hard. “You have enough water?” Both soon turned back, moving slowly down unlit rocky switchbacks. An owl chittered.
“You definitely feel the heat, but the nights are better,” Mr. Plautz said. “A lot of people hike right now instead of during the day because it is a lot cooler.”
Phoenix, which had 128 days at or above 100 degrees Fahrenheit last year, is one of the hottest and fastest-warming cities in the United States. Although it is on the leading edge, it is not alone: Most American cities are expected to drastically heat up in the next decades. Many may have summers with heat waves and triple-digit days — summers that resemble Phoenix today.
Here in the Valley of the Sun, that means work and play shift into the cooler hours. Neighborhoods thrum with activity at dawn and dusk when residents hike, jog and paddleboard. In the hottest months, the zoo opens at 6 a.m., for the benefit of both animals and visitors. And across the city, certain construction work starts in the middle of the night — not only for the safety of workers, but also because even some building materials can be affected by intense heat.
For workers doing concrete pours, jobs can start close to midnight so the material doesn’t get too hot or dry too quickly and later crack. At 1:30 a.m., on a construction site near Peoria, a Haydon Building Corporation crew listened for the approach of mixer trucks along a dusty dirt road marked with green flares. Moths and grasshoppers dashed against the stadium lights.
The crew was working on a bridge, hooking future housing developments to the suburban road matrix.