HAPPY CAMP  (AP) — Air crews battling a fast-moving fire threatening 250 homes in a Northern California forest were using clear skies to get going earlier than usual on Friday, which should help with the firefight, fire officials said.

The weather has kept skies over the fire in the Klamath National Forest smoky, preventing air drops until late in the afternoon. But clear skies were expected over the next several days, which should allow planes and helicopters to move freely, Jake Rodriguez, an information officer said.

The lightning-sparked fire complex near the logging and gold mining town of Happy Camp grew dramatically over the past several days and was threatening about 250 rural homes. Some of the homes were under mandatory evacuation orders, which were expanded Thursday night.

The two largest fires in the complex — among numerous fires that broke out when a thunderstorm moved through the area on Aug. 11 — had burned through about 69 square miles as of Friday morning, an increase of about 20 square miles from a day earlier. One was 10 percent contained. There was zero containment on the other.

Firefighters have been hampered by steep terrain, winds that have carried embers ahead of the main blazes and sparked spot fires, and low humidity.

“We’ve also seen a lot of trees falling, which presents a hazard to firefighters,” Rodriguez said.

The humidity was expected to be a little higher on Friday. The wind pattern could also push the fire away from threatened homes, Rodriguez said.

Crews, meanwhile, were getting the upper hand on another set of fires about 18 miles to the south in the Klamath National Forest that also forced evacuations. The fire, which has burned through about 62 square miles, was 73 percent contained. Most of the mandatory evacuations were lifted this week.