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)

Photo by: Manuel Balce Ceneta

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)