Firefighters continued to make gains Thursday on the Wye fire in Lake and Colusa counties, with full containment expected Sunday, a day earlier than previous estimates, officials said.

Cal Fire reported 755 firefighters were battling the remnants of the blaze, following the release of about 470 firefighters, who were dispatched to other fires in California, spokeswoman Cherie Alver said.

The fire, which broke out Sunday in two locations, is now 85 percent contained, up from 70 percent on Wednesday.

No structures are threatened and all evacuation orders have been lifted.

"That's encouraging," Alver said.

Work on Thursday involved strengthening control lines around the blaze, which has burned nearly 8,000 acres. Mop-up efforts will continue for several days, Alver said.

Winds of 10 to 15 mph were blowing out of the west on Thursday, the same direction but a bit stronger than on Wednesday.

Temperatures in the 101- to 105-degree range were forecast.

Air quality conditions in the Lake County basin improved, with the wind pushing smoke out of the area, the Lake County Air Quality Management District said.

The agency forecast "good" air quality for most of Lake County, but said areas near the active fire may experience "moderate" to "unhealthy" air intermittently during the day. The greatest concern is in Clearlake Oaks, Spring Valley and portions of Clearlake.

Residual haze and particulates from the wildfire may occasionally affect parts of Lake County until the fires are out, the agency said.

Highway 20 reopened Wednesday in both directions with a 45-mph limit through the area of the fire.

Motorists are asked to "use extreme caution" when driving in areas where fire crews and PG&E repair crews are working, the Lake County Sheriff's Office said.

The 45-mph limit will be "strongly enforced" by the Sheriff's Office and the CHP.

Traffic on Highway 20 east of the intersection with Highway 53 had been limited to one direction, with CHP escorts and lengthy delays earlier in the week.

Cal Fire has suspended all outdoor burning permits because of the extreme danger of wildland blazes.

"The Burn Ban suspends all residential burn permits, forest management, hazard abatement, and other industrial-type permitted burning within the 31 million acres of State Responsibility Area," Cal Fire spokesman Daniel Berlant said in a news release.