Dozens of wildfires were burning in Oregon on Friday after thunderstorms delivered thousands of lightning strikes across a landscape that had been left parched by drought.

Ted Pierce, manager of the Northwest Interagency Coordination Center, said that 140 new fires were reported on Wednesday and Thursday and that they had burned more than 30,000 acres so far.

“We’re still finding fires,” Mr. Pierce said on Friday afternoon.

About 11,000 people were under one of Oregon’s three levels of evacuation warnings, which range from one, telling people to be ready to leave, to three, telling them to leave immediately, according to the Oregon Office of Emergency Management. It said about 1,200 were under the most urgent order to evacuate immediately.

The fires also brought smoke that was spreading across the Pacific Northwest on Friday afternoon, with the most unhealthy air over southwestern, central and northeastern Oregon.

Oregon’s peak wildfire season runs between July and September, and this one was predicted to be particularly active with widespread drought across the state. Oregon received significantly less snow than usual last winter, and the little that did fall melted away early amid record warmth.

That left the landscape primed to burn on Wednesday and Thursday when thunderstorms raced across the state. Thunderstorms can sometimes help reduce wildfire risk if they bring enough rain, but that was not the case with these storms.

“They were moving so quickly that we didn’t get a lot of accumulation,” said Rebecca Muessle, a meteorologist with the National Weather Service office in Portland.

Most areas recorded a tenth to a third of an inch of rain, which is not enough to put out wildfires or prevent them from igniting.

When thunderstorms pass by an area without sending much rain to the ground, they can still whip up strong winds and dry lightning. Many of the fires in 2020, one of the worst West Coast fire seasons in recent memory, were sparked this way.

While the cause of many of these fires can’t be confirmed until investigations are complete, more than 3,000 lightning strikes were recorded, according to the Weather Service.

The new blazes ignited as firefighters continued to battle what Gert Zoutendijk, a spokesman for the Oregon state fire marshal, called the “first big fire of the season,” the 13,000-acre East Evans Creek fire near Medford. That fire ignited a week ago, on July 10, when a vehicle crash knocked over a power line, he said. The fire has forced about 500 people to evacuate their homes, and hundreds of others were under evacuation warnings.

“This one just went so fast with the winds and got out of control into terrain that wasn’t accessible to firefighters,” Mr. Zoutendijk said.