Firefighters who experienced a short respite from raging wildfires when cooler temperatures descended on California are gearing up for another wave of heat and wind that could stoke more blazes.In Northern California, where the state’s largest wildfire in history, the August Complex, has been burning since midsummer, weather forecasters are warning of “extreme fire weather conditions.”And in the fire-ravaged state of Washington, forecasters said temperatures could reach the 80s in some areas by Tuesday.The culprit is a strong high-pressure system parked over the West Coast, said meteorologist Kristen Stewart of the National Weather Service office in Oxnard, California.”The high pressure will keep the heat on for the week,” she said.Higher temperatures were expected to develop in Southern California on Monday along with offshore winds that could last through at least Thursday, she said. Temperatures are likely to reach the triple digits in inland valleys, she said.A fire weather watch was in effect Monday for Los Angeles and Ventura counties.The California Department of Forestry and Fire Protection said much of Northern California was under a red-flag fire warning of critical fire conditions for Sunday and Monday.Pacific Gas & Electricâ€”the utility whose equipment was blamed for the state’s deadliest fireâ€”announced Saturday that it would turn off electricity for 89,000 customers in phases as a precaution starting Sunday morning.It was only two weeks ago that the largest wildfire in state history grew into a 870,200-acre behemoth on federal land north of Sacramento. The blaze, which started Aug. 16, was still burning and only 43 percent contained Saturday, according to Cal Fire.”Firefighters are getting a break, but not much,” said Cal Fire spokesperson Christine McMorrow. “We are getting a handle on the current fires, even some of those that have been burning since August.”The agency said 8,000 wildfires have burned more than 3.6 million acres since the beginning of the year. Since mid-August, there have been 26 fire-related fatalities, it said.McMorrow said state firefighters were nonetheless ready should the weather whip up flames that are usually sparked by humans.”Weâ€™re positioning resources and evaluating the weather day-by-day, hour-by-hour to make sure our troops are ready to go,” she said.Dennis RomeroDennis Romero writes for NBC News and is based in Los Angeles.