(CBS SF) — Firefighters continued to make progress on the three major lightning sparked wildfires that have been burning for weeks in the Bay Area, as temperatures are set to soar again Labor Day weekend.

SCU Complex:
The SCU Lightning Complex is 86 percent contained at 396,624 acres, and full containment is expected by Sept. 12, Cal Fire said Saturday.

Overnight, the fire continued to creep through areas of unburnt brush, assisted by the nightly drop in humidity and warmer temperatures, according to Cal Fire. On Saturday, fire crews will continue to strengthen control lines.

Lightning on Aug. 16 sparked the SCU blazes, burning in Santa Clara, Alameda, Contra Costa, San Joaquin, Stanislaus, Merced and San Benito counties. Two people have died and three people have been injured in the fires. The SCU complex has destroyed 105 structures.

CZU Complex:
In Santa Cruz and San Mateo counties, the CZU Lightning Complex was 61 percent contained at 86,509 acres on Saturday morning, Cal Fire said.

One person has died and another injured since the fires were sparked Aug. 16. The blazes have destroyed 925 homes, three multiple residential buildings and 174 commercial or mixed commercial buildings.

More than 7,600 structures remain threatened and about 1,800 people have been evacuated. Resource and local assistance centers for residents affected by the fires are located at Kaiser Permanente Arena on 140 Front Street, Santa Cruz and at Pescadero Elementary School on 620 North St. in Pescadero.

LNU Complex:
The LNU Lightning Complex burning in North Bay counties reached 89 percent containment by Saturday morning, at 375,209 acres, Cal Fire said.

Overnight, firefighters saw limited growth on the Walbridge and Hennessey fires, and many areas remain under an evacuation warning. As with the other two blazes, crews are continuing to work containment lines and fire suppression repair teams remain active.

Five people have died and four others have been injured since the fires were sparked Aug. 17 and spread across Napa, Solano, Lake and Yolo counties.

Nearly 1,500 structures have been destroyed and 1,350 are threatened, Cal Fire said.

The Bay Area is set to begin three days of high temperatures starting Saturday, with inland highs reaching well into the 100s. An Excessive Heat Warning has been declared by the National Weather Service for much of the region from 11 a.m. Saturday through 9 p.m. Monday.

READ MORE: Bay Area Cooling Centers Offer Relief From Heat Wave

Following the heat wave, the Bay Area could see increased risk for new fires, due to offshore winds that could gust up to 50 mph in some locations. The Weather Service has also declared a Fire Weather Watch for the North Bay mountains and East Bay hills from Monday evening through Wednesday morning.

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