SPOKANE — Calmer winds and cooler temperatures were allowing firefighters to go on the offensive Monday against a destructive wildfire that has charred hundreds of square miles of terrain in Washington State.

The Carlton Complex of fires in north-central Washington had burned about 379 square miles, fire spokesman Andrew Sanbri said Monday.

“There is optimism in the air, but we don’t want to give the impression that all is good,” Sanbri said. “Things are improving.”

The fire was just 2 percent contained on Monday.

Firefighters planned to aggressively protect some houses near Libby Creek on Monday by keeping the flames from jumping the waterway, Sanbri said. Okanogan County Sheriff Frank Rogers estimates that 150 homes have been destroyed already, but suspects that number could be higher. The fire is being blamed for one death.

Firefighters on Monday had also planned to burn some fuel on the north side of the fire to help build a fire line, but that operation was canceled, fire spokesman Don Carpenter said.

Firefighters were also hampered by the loss of electricity in the area, thanks to downed power lines and poles, which hurt communications. There was no estimate on when utilities would be restored.

The forecast for Monday and Tuesday called for lighter winds and lower temperatures, said Spokane-based National Weather Service meteorologist Greg Koch.

Then on Wednesday a “vigorous” front is expected to cover Washington, bringing rain to much of the state. But it will also bring lightning, he added.

“The benefits of the system are still up in the air,” Koch said. “We may get some rain where we need it, but we may also experience some lightning that could cause some new ignitions.”

The fire has created smoky conditions and reduced air quality in much of eastern Washington and northern Idaho.

Rogers said one man has died of an apparent heart attack while fighting the fire near his home. Rob Koczewski, 67, was stricken on Saturday while he and his wife were hauling water and digging fire lines near their home. Rogers said Koczewski was a retired Washington State Patrol trooper and U.S. Marine.

There are more than 1,600 firefighters battling the flames, assisted by more than 100 fire engines, helicopters dropping buckets of water and planes spreading flame retardant, Sanbri said.

Many towns in the scenic Methow Valley remain without power and have limited landline and cellphone service. Okanogan County Public Utility District officials told KREM that fully restoring power to the area could take weeks.

Karina Shagren, a spokeswoman for the state’s Military Department, said 100 National Guard troops were on standby, and up to 1,000 more in Yakima could receive additional fire training. Active-duty military could be called in as well, Shagren said.