A piece of drift wood lies on the cracked mud in a dry cove at Morse Reservoir in Noblesville, Ind., Friday, July 6, 2012. The reservoir is down nearly 4 feet from normal levels and being lowerer 1 foot every 5 days. Temperatures again exceeded 100 degrees in Central Indiana. The National Weather Service said the record-breaking heat that has baked the nation’s midsection for several days was slowly moving into the mid-Atlantic states and Northeast. Excessive-heat warnings remained in place Friday for all of Iowa, Indiana and Illinois as well as much of Wisconsin, Michigan, Missouri, Ohio and Kentucky. (AP Photo/Michael Conroy)

Mikel Welch, 9, floats on his back as he cools off in a fountain Friday, July 6, 2012, in St. Louis. Excessive-heat warnings remained in place Friday for all of Iowa, Indiana and Illinois as well as much of Wisconsin, Michigan, Missouri, Ohio and Kentucky. (AP Photo/Jeff Roberson)

With game-time temperatures in the 90s Pittsburgh Pirates' James McDonald wipes his face in the dugout during the eighth inning of a baseball game against the San Francisco Giants in Pittsburgh, Friday, July 6, 2012. The Giants won 6-5. (AP Photo/Gene J. Puskar)

Ted Georges, of Columbus, Ohio, jumps into a pool from a recreational vehicle as Andrew Florance, left, of Naples, Fla., sprays him while trying to beat the heat before the races in the infield of the Daytona International Speedway auto race in Daytona Beach, Fla., Friday, July 6, 2012. Watching them are Chris Fuqua, second from left, Zach Crandell, center, and Bob Holtz, right. (AP Photo/Phelan M. Ebenhack)

A sun bear reacts to triple-digit temperatures at the Henry Doorly Zoo in Omaha, Neb., Friday, July 6, 2012. The temperature reached 103 degrees Fahrenheit (39.5 Celsius) Friday. (AP Photo/Nati Harnik)

Perspiration collects on construction worker David Macmullen's face in the afternoon heat, Friday, July 6, 2012, in Philadelphia. The National Weather Service said the record-breaking heat that has baked the nation’s midsection for several days was slowly moving into the mid-Atlantic states and Northeast. Excessive-heat warnings remained in place Friday for all of Iowa, Indiana and Illinois as well as much of Wisconsin, Michigan, Missouri, Ohio and Kentucky. (AP Photo/Matt Rourke)

Summer Santa Claus Tom Osborn of Taylor, Pa. a member of the Greater Scranton Jaycees, cools his feet in a pool of ice at Lackawanna County Courthouse Square during First Night festivities held in downtown Scranton, Pennsylvania on Friday, July 6, 2012. (AP Photo/The Scranton Times-Tribune, Butch Comegys)

A woman waiting in the crowd to hear President Barack Obama, at Carnegie Mellon University, shields herself from the sun with a cloth as temperatures approach 90 degrees, Friday, July 6, 2012, in Pittsburgh.. Obama is on a two-day bus campaign trip through Ohio and Pennsylvania (AP Photo/Keith Srakocic)

The ground is cracked at the edge of an irrigated corn field near England, Ark., Friday, July 6, 2012. Oppressive heat is slamming the middle of the country with record temperatures that aren’t going away after the sun goes down. (AP Photo/Danny Johnston)

A woman is taken away on a stretcher after being effected by the heat while waiting for President Barack Obama at Carnegie Mellon University in Pittsburgh, Friday, July 6, 2012. Obama is on a two-day bus campaign trip through Ohio and Pennsylvania (AP Photo/Keith Srakocic)

Jake Wenz, 12, jumps off the high board at Centennial Beach in Naperville, Ill. on Friday July 6, 2012. There's been no relief day or night from a scorching heat wave in the central U.S., and the deadly temperatures were heading east Friday after Midwest cities like Chicago, St. Louis and Milwaukee set record highs.(AP Photo/Daily Herald,Bev Horne )

Guy Clark, of Ponca City, Okla., takes a drink of water before competing in the Ranch Sorting Championship at State Fair Park in Oklahoma City, Friday, July 6, 2012. (AP Photo/Sue Ogrocki)

Barbara Rivers, 65,left, wipes away sweat as she gets a comforting pat on the shoulder from her cousin Fate Roy Harris, 69, outside her home in the Palmer Woods neighborhood of Detroit on July 5, 2012. She has been without power for 24 hours since summer storms knocked it out. The National Weather Service reported late Thursday that the record-breaking heat that has baked the nation's midsection for several days was slowly moving into the mid-Atlantic states and Northeast. That forecast followed excessive-heat warnings Thursday for all of Illinois and Indiana, as well as parts of Iowa, Minnesota, Wisconsin, Missouri, Kentucky, Ohio and Michigan. (AP Photo/Detroit News, Brandy Baker) DETROIT FREE PRESS OUT; HUFFINGTON POST OUT

This is the Weather Underground national forecast for Saturday, July 7, 2012. Extreme heat returns to the East as high pressure shifts eastward. Meanwhile, a cold front will drop across the Northeast and Midwest with showers and thunderstorms. Additional thunderstorms will continue in the Deep South and the West. (AP Photo/Weather Underground)

Sophie, 3, from Connecticut, frolics with a water sprinkler set up at the National Mall near the Lincoln Memorial, rear, in Washington Saturday, July 7, 2012. The heat gripping much of the country is set to peak Saturday in many places, including some Northeast cities, where temperatures close to or surpassing 100 degrees are expected. (AP Photo/Manuel Balce Ceneta)

Eric Midence, 12, cools off in the Forest Hills Park sprayground on Friday, July 6, 2012 in Durham, N.C. The National Weather Service reported late Thursday that the record-breaking heat that has baked the nation's midsection for several days was slowly moving into the mid-Atlantic states and Northeast.(AP Photo/The Herald-Sun, Christine T. Nguyen)

Amari Swint, 8, front, of Philadelphia, and Nia Bailey, 8, of Washington, play in an inflatable pool during the seventh annual block party on Newton Street in northwest Washington, during record heat with temperatures in the triple digits, Saturday, July 7, 2012. (AP Photo/Jacquelyn Martin)

This photo provided by the Chicago Zoological Society shows Hudson, a polar bear at Brookfield Zoo in Brookfield, Ill., enjoysing a swim after jumping into his pool Saturday, July 7, 2012, as a heat wave continues throughout the Midwest. (AP Photo/Chicago Zoological Society, Jim Schulz)

Avery Gass, 4, slips her way through streams of cooling water, Friday, July 6, 2012, at the Thorton Murphy Park splash pad in Spokane, Wash. The National Weather Service says the high pressure system responsible for heat in much of the country is building into the Northwest this weekend. (AP Photo/The Spokesman-Review, Dan Pelle)

Debby Lutz, top, of Wilson, Pa. and her mother Ann Lutz, bottom, sit in the middle of the Lehigh River Friday, July 6, 2012 near Hugh Moore Park. The National Weather Service reported late Thursday that the record-breaking heat that has baked the nation's midsection for several days was slowly moving into the mid-Atlantic states and Northeast.(AP Photo/The Express-Times, Matt Smith)

U.S. Postal Service letter carrier Monique Miller drinks from a bottle of water as she delivers mail in the Feltonville section of Philadelphia on Saturday July 7, 2012. Temperatures of more than 100 degrees were forecast in Philadelphia and excessive heat warnings were issued for several states in the Midwest as a heat wave continued. (AP Photo/Joseph Kaczmarek)

Kevin Sanabria, 10, plays in a small waterfall in Trenton, N.J., Saturday, July, 7, 2012. People were coping as temperatures in the region climbed into the high 90s. (AP Photo/Mel Evans)