BOISE, Idaho -

Idaho wildfires kept crews busy as temperatures across the state soared to near 100 degrees.

The Boise National Forest reported on Monday a 50-acre fire about four miles from the Bogus Basin Mountain Resort ski area above Boise was burning in grass and ponderosa pine trees.

Forest Service spokesman David Olson said no structures were threatened by the Pine Creek Fire.

Still, a pair of 20-person crews, as well as three helicopters, were responding to the flames.

To the north along the Salmon River, firefighters Monday reported making excellent progress on the Rough Creek Fire, including building fire lines and dropping water from the river using helicopters.

Six Hotshot crews were maintaining a night shift on the fire lines.

That fire was burning about six miles from Riggins.