Much of America is roasting. A lengthy, blistering heat wave—a "heat dome," in meteorological parlance—is blanketing the eastern half of the United States. Heat indexes soared on July 21 and are expected to approach 105F (40.5C) on July 22. In Philadelphia, 8-year-old Jazia Pratt fills a bucket with water from a fire hydrant in the afternoon heat on July 18, 2011. Photographer: Matt Rourke/AP

Much of America is roasting. A lengthy, blistering heat wave—a "heat dome," in meteorological parlance—is blanketing the eastern half of the United States. Heat indexes soared on July 21 and are expected to approach 105F (40.5C) on July 22. In Philadelphia, 8-year-old Jazia Pratt fills a bucket with water from a fire hydrant in the afternoon heat on July 18, 2011. Photographer: Matt Rourke/AP

Heat Wave Engulfs the U.S.

Philadelphia: Water, Water, Everywhere
Philadelphia: Water, Water, Everywhere

Much of America is roasting. A lengthy, blistering heat wave—a "heat dome," in meteorological parlance—is blanketing the eastern half of the United States. Heat indexes soared on July 21 and are expected to approach 105F (40.5C) on July 22. In Philadelphia, 8-year-old Jazia Pratt fills a bucket with water from a fire hydrant in the afternoon heat on July 18, 2011. Photographer: Matt Rourke/AP

New York City: Hot in the City
New York City: Hot in the City
A woman sits on the promenade near New York's Carl Schurz Park on July 21, 2011. Photographer: Timothy A. Clary/AFP/Getty Images
South Windsor: A Dog Day Afternoon
South Windsor: A Dog Day Afternoon
Buck cools off with bottled water provided by owner Sue Anderson of South Windsor, Conn., during an American Legion baseball game at peak heat on July 20, 2011. Photographer: Jim Michaud/Journal Inquirer/AP
Philadelphia: Lady in Red
Philadelphia: Lady in Red
Bathers beat the midday heat at the Devil's Pool in Philadelphia's Wissahickon Valley Park on July 20, 2011. Photographer: Matt Rourke/AP
Detroit: Chilling on Asphalt
Detroit: Chilling on Asphalt

From left, Derrien McClendon, 12, Cartier Williams, 4, Kobe Williams, 9, and Nathaniel Mosley, 9, lie in water from an open hydrant in Detroit on July 21, 2011. A heat wave has been smothering the Midwest, with heat indexes scoring well over 100 in most places. Photographer: Paul Sancya/AP

Flint: Everyone Into the Pool
Flint: Everyone Into the Pool
Nigel Crader, 12, flips over Tyquavious Brown, 10, as Shamir Spencer shields herself from the splashes while playing in a pool in their front yard in Flint, Mich., on July 19, 2011. Hot and humid weather arrived this week and is forecast to stick around into the weekend. Photographer: Ryan Garza/The Flint Journal/AP
Detroit: Riding the Wave
Detroit: Riding the Wave

A skateboarder cruises through heavy spray from an opened fire hydrant in Detroit on July 21, 2011. The U.S. National Weather Service says Detroit's temperature is expected to reach 100. Photographer: Carlos Osorio/AP

Bay City: Gotta Stay Hydrated
Bay City: Gotta Stay Hydrated
Rick Vermeulen cools off with a drink from his water cooler as he takes a break from 95-degree heat on July 21, 2011, in Bay City, Mich. Photographer: Michael Randolph/The Bay City Times/AP


Marne: Ginormous Fan
Marne: Ginormous Fan

Luke McCrory, 5, from Coopersville, cools off in front of a giant fan at the Berlin Fair in Marne, Mich., on July 19, 2011. Photographer: Cory Morse/The Grand Rapids Press/AP

Chicago: Play Ball
Chicago: Play Ball

A baseball fan cools off in Chicago after a game between the Philadelphia Phillies and the Chicago Cubs on July 20, 2011. Photographer: Nam Y. Huh/AP

Franklin: More Ice, Please
Franklin: More Ice, Please
Mayor Fred Paris of Franklin, Ind., pours one of 250 bags of ice into the Franklin Memorial Swimming Pool on July 21, 2011. Photographer: Darron Cummings/AP
Dayton: Wet Enough for You?
Dayton: Wet Enough for You?

Mike McGinnis, 10, runs through a sprinker and gets hit with a torrent of water from a pail on July 17, 2006, in Dayton, Ohio. Photographer: Bill Reinke/Dayton Daily News/AP

Colorado Springs: Summertime!
Colorado Springs: Summertime!
Trelynn Wakins, 10, lies happily in the Julie Penrose Fountain at America the Beautiful Park in Colorado Springs, Colo., on July 20, 2011. Photographer: Genna Ord/The Colorado Springs Gazette/AP


Omaha: Ah, Relief
Omaha: Ah, Relief
A girl cools off in mist at Omaha's Henry Doorly Zoo on July 18, 2011. Photographer: Nati Harnik/AP
Wichita: Water Break
Wichita: Water Break
Participants in Drums Across Kansas, which features eight elite drum-and-bugle corps from around the country, take a water break on July 18, 2011, near Wichita, Kan. Photographer: Mike Hutmacher/The Wichita Eagle/AP