Most wildfires in the country are caused by humans, according to the U.S. National Park Service.
But fire officials said nature is a possible cause too.
"Could be started by lightning strikes or a storm," said Izak Hamilton, spokesperson with Clackamas Fire.
And that's what some are concerned will happen Tuesday in Oregon.
"Good chance, especially on the east side of the Cascades," said Dave Salesky, KATU's meteorologist.
Usually, of course, rainwater can help.
But Salesky said that would not be the case Tuesday.
"You have moisture of course with those storms. But the moisture in those storms, that rainfall, never reaches the ground. The air temperatures are so high, it evaporates before reaching the ground," he said.