Extreme heat claims more lives

BRIAN WILLIAMS, anchor: Problem for much of the country tonight continues to be extreme heat. A deadly heat wave now in its second month with excessive heat warnings in effect across the country tonight and 18 states hitting temperatures above 100 degrees today alone. NBC 's Lee Cowan is in blisteringly hot Phoenix , Arizona , tonight, with more.

LEE COWAN reporting: Phoenix knows hot. But with a predicted high of 115 today, even the desert loving ostriches at the zoo had to be hosed down.

Unidentified Woman #1: I've lived here my whole life and it's just -- and even for me it just gets hotter and hotter every summer.

COWAN: Arizona joins at least 17 other states today that topped the century mark. Twelve are under an excessive heat warning tonight, all putting a drain on power grids burning up from overuse.

Unidentified Man: I'm probably drinking close to 90 ounces of water a day. A lot.

COWAN: The suffering was everywhere. In Dallas , the heat wave logged its 33rd day in a row with temperatures over 100.

Unidentified Woman #2: It feels like the worst one so far. I've been here 15 years.

COWAN: But misery over the mercury is more than just a physical discomfort. Here in Arizona and Texas and Oklahoma , it's just contributing to one of the worst droughts since the 1950s .

MIKE SEIDEL reporting: Nothing can grow. Everything's dying on the vine, in the fields, and ranchers are sending their cattle to market early because they don't have enough grain and water to feed them.

COWAN: In Georgia , it's been so hot they're holding football practice before sunup, a precaution after a player collapsed and later died. From a mother's loss to losses in the field to a simple loss of patience, the heat is taking its toll. Lee Cowan, NBC News, Phoenix.