BOISE, Idaho (AP) — Wildfire season accelerated in Idaho on Thursday with flames spreading across sagebrush steppe in the southwest and burning through forests in mountain regions.

Officials shut down U.S. Highway 95 again in southwest Idaho due to a 187-square-mile fire whipping through grassland and sagebrush.

Fire spokeswoman Carrie Bilbao says light rains last spring boosted growth of invasive cheatgrass that then dried and helped set the stage for the massive fire that has destroyed at least 15 square miles of top-level sage grouse habitat.

In northern Idaho, mandatory evacuations are in place in a rural area near the town of Kamiah as a complex of fires has burned about 3 square miles.

In the Boise National Forest in central Idaho, crews are trying to stop a 500-acre fire burning in heavy timber.