John Rohlfing, 38, takes a drink as he works on the construction of his new home Thursday in North Aurora, Ill. He started at 6:00 a.m. and quit at 11:00 a.m. because of triple-digit temperatures. Robert Ray/AP hide caption

itoggle caption Robert Ray/AP

In Silver Spring, Md., on Monday, Matt MacCartney was one of many workers dismantling fallen trees that took down power lines. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

Volunteer John Kelley (left) leads an exercise class at a senior center in Oklahoma on Monday. Centers such as these offer seniors a cool place to go during heat waves. Sue Ogrocki/AP hide caption

itoggle caption Sue Ogrocki/AP