The National Weather Service declares the last week of June Lightning Awareness Week.
Lightning Safety Specialist John Jensenius said the rule is when thunder roars, go indoors.
"If you hear thunder, even a distant rumble, you need to get inside right away," Jensenius said. "The reason for that rule is the fact that you can hear thunder about 10 miles from the storm, and lightning can strike outward for about 10 miles from the storm."
The best place to be is inside a substantial building.
"By 'substantial building,' we mean one that has four walls, a roof and has wiring or plumbing in it so that if lightning does strike the building, it will follow the wiring or plumbing to the ground and will leave the people inside alone," Jensenius said.
Don't use things connected to plumbing or wiring during a thunderstorm in case the building is struck by lightning.
A car with a metal roof is also a safe place to be if a building isn't available.
About two-thirds of people struck by lightning are having fun outdoors when it happens.
"Many of those activities require extra time to get to a safe place," Jensenius said. "People may be out on a lake fishing. They may be some distance from safety."
In the last decade, 322 Americans died after being struck by lightning. Just two of those happened in Oklahoma.
Oklahoma has an average of 1.1 million lightning strikes a year over the last decade. Tulsa has a chance of thunderstorms beginning Friday and lasting through the weekend.
