WENATCHEE, Wash. (AP) — Firefighters battled stubborn blazes that kept residents from homes in Montana, Wyoming and Washington as authorities worried the weather could worsen the volatile situation.

High temperatures, lower humidity and greater instability increase the potential for fires to grow, said Ed Delgado, the national predictive services meteorologist for the National Interagency Fire Center in Boise, Idaho.

“Our biggest concern right now is existing fires,” he said. “We’re not expecting lightning over the next few days, although that doesn’t alleviate the potential for human-caused fires, especially as we get into camping and hunting seasons.”

Seven homes were destroyed and hundreds of people were evacuated near Casper, Wyo., where a wildfire burned almost 24 square miles. In western Montana, fire crews were struggling to control a blaze that prompted an evacuation order for 400 houses west of Hamilton.

In eastern Washington, a grass and sagebrush fire that ballooned from 11,000 acres to more than 60,000 — or 95 square miles — before winds died down was blamed for destroying three homes near Grand Coulee, a fire official said.

As winds eased, crews were hopeful they could gain ground on dozens of fires sparked by weekend lightning storms. But more evacuation orders were issued Tuesday as a wildfire moved into the hills west of Wenatchee, a fruit capital on the banks of the Columbia River.

More than 150 homes were evacuated as the fire burned about 140 miles east of Seattle. About 160 firefighters gathered to help fight the blaze, which covered 1,000 acres.

Only a shed has been lost near Wenatchee, and no injuries were reported at what appeared to be the most threatening of numerous lightning-sparked wildfires in the state.