* West Virginia hardest hit state
* Heat wave to continue through weekend
By Ian Simpson
LEWISBURG, W.V., July 5 (Reuters) - Six days after violent storms hit the eastern United States, the state of West Virginia was struggling to recover on Thursday, with nearly a third of electricity customers still without power and new storms putting more customers in the dark.
Electric utilities said more than 550,000 homes and businesses are without power from Ohio to Virginia, leaving them without air conditioning amid a heat wave.
West Virginia, with a population of about 1.9 million people, was the hardest hit. Utilities warned that some people could be without power for the rest of the week in the worst-hit areas.
The temperature in Charleston, West Virginia's largest city, reached 93 degrees Fahrenheit (34 Celsius) on Thursday and was expected to top 100 degrees (38 C) on Friday and Saturday before returning to near normal levels in the mid 80s by Monday, according to Accuweather.com.
More outages have resulted from a fresh batch of damaging storms that pushed across southern West Virginia, Tennessee, Kentucky and North Carolina Thursday afternoon.
A cluster of strong storms drifted across Ohio Thursday morning, causing power outages and knocking a 16-foot tree branch onto a bed in a house on Sheffield Lake near Cleveland.
"At least I have firewood," said Harry May, 59. He and his wife both work early shifts, so they were away from the house when the branch broke through the roof of their house and landed on Harry's side of the bed.
The continued heat wave was bad news for Midwest farmers, with the corn crop suffering from drought in the middle of a crucial growth phase.
The U.S. Drought Monitor showed an expanding area of abnormally dry and drought conditions in Illinois, Indiana, Ohio and Missouri. Corn and soybean prices jumped to new highs on Thursday as the heat scorched crops.
"It's not only abnormally dry, but now you have 100 degree heat combined with the ongoing drought and it's too much for the crop," Accuweather.com senior meteorologist Alex Sosnowski said.
The Midwest and East should start seeing more normal temperatures next week, when the extreme heat moves west, bringing triple-digit temperatures to parts of Idaho, Utah, Washington and Oregon.
The temperature in Chicago hit a record 103 degrees Thursday, before dropping 19 degrees with the arrival of a thunderstorm in the early afternoon. Summer school was canceled at 21 public school buildings without air conditioning. Part of Columbus Drive near downtown was closed after pavement buckled.
Around a ground-level fountain near downtown Chicago's Daley Plaza at lunchtime, more than a dozen people were resting their feet in the cool water.
"Any time you can cool off one part of your body, it helps," said Mary Moore, 56, of Chicago, who was dipping her feet in the fountain during a break from jury duty. She said she didn't mind the sunny weather. "I prefer it to the winter," she said.
On Saturday, Washington, D.C., could break its all-time record of 106 degrees (41 C) set in 1930, Sosnowski said.
The storms last Friday crossed the eastern United States with heavy rain, hail and winds reaching 80 miles per hour (129 kph), leaving more than 4 million homes and businesses without power. The storms and the record heat that followed have killed at least 23 people.
American Electric Power Co Inc of Ohio said about 224,000 homes and businesses remained without power in West Virginia and Virginia, and about 144,000 in Ohio were powerless.
FirstEnergy Corp of Ohio said it was working to restore power to more than 111,000 customers in West Virginia and Maryland. That was down from about the initial 566,000 homes and businesses affected by the storms.
Illinois-based Exelon Corp said its Baltimore Gas and Electric unit still had about 53,000 customers out in Maryland.
Virginia power company Dominion Resources Inc said about 29,000 customers were still without power in its Virginia and North Carolina service areas.
Washington, D.C.-based Pepco Holdings Inc said it had about 20,300 customers without power in the District of Columbia and Maryland, and about 16,100 were out in New Jersey.