"And people need to make sure their houses are wired for a generator before they hook one up," Petry said.
Gasoline must be stored in a safe, dry place.
"That way people don't create a worse danger for themselves and the community," he said.
Gasoline also must be cycled through the generator on occasion, Petry said.
"Gas can go bad," he said.
This is one of the worst situations Petry has seen when it comes to a natural disaster. He pointed out that many areas of the state were without power for more than seven days.
And with the excessive heat, more severe thunderstorms could be the norm over the summer, he said.
"With the excessive heat we've already had, I expect this to be a bad summer," Petry said.
At least this week temperatures are expected to dip, said Joe Merchant, a meteorologist with the National Weather Service's Charleston office.
A cold front that has moved into the area should keep temperatures in the mid 80s for the remainder of the week, he said.
"But we're in the warmest part of our year, so that doesn't mean temperatures won't climb back into the '90s again," he said.
The derecho that blew through the area wreaking havoc was a rare occurrence in the Mountain State but not unheard of.
The last time a derecho was recorded in West Virginia was April 9, 1991, he said.
"It began in Arkansas and it moved through the entire state."