Northern California is bearing the brunt of wildfires that have destroyed scores of homes and consumed huge swaths of land. The state has seen 1,000 more wildfires so far this year compared to the average, many of them in northern forest areas left bone-dry by the drought.
But Southern California is about to enter its traditional fire season, and officials worry that the destruction to the north offers a grim preview of what's ahead.
"Conditions are ripe, and it only takes one day of hot, dry weather with Santa Ana winds for a large wildfire to cause destruction," said Daniel Berlant of the California Department of Forestry and Fire Protection.
The latest forecast from the National Weather Service released Wednesday only added to the concern. Northern California typically gets 30% to 40% of its rain in the next three months, but meteorologists said they see largely dry conditions ahead. The drought outlook is similar for the south.
Much of California is susceptible to wildfires, but fire behavior differs by region.
In Northern California, many of the big fires have occurred in remote forest and wildland areas, ignited by summer lightning storms.
Typically, these forests get plenty of rain in the winter and fall, giving them a defense against the lightning fires. But the drought has left the areas unusually dry, allowing fires to spread much more quickly into rugged terrain that is difficult for firefighters to reach.
"Once they get started, it's a matter of what has to burn," U.S. Forest Service fire ecologist Neil Sugihara said.
Many of these forests have not burned in decades, leaving thick stands of dry foliage. The Happy Camp Complex fire in Klamath National Forest, the largest on record this year in the state, has been burning dense forestland since lightning struck more than a month ago.
Fires have consumed 366,285 acres of national forest in Northern California this year, compared to 84,109 acres during the same period in 2013. Those fires have already surpassed the five-year average for lost forest acreage in the entire state, which is 214,391 acres.
In the last two weeks, nearly 200 structures have been burned from the Oregon border to the outskirts of Yosemite.
So far this summer, Southern California has been fortunate. In contrast to the northern part of the state, the vast majority of fires are started by humans and spread by dry, hot Santa Ana winds.
Fire officials said they have seen fewer fire starts than normal, and moderate wind conditions. Some heat waves have even come with a little humidity.
"And even though we've had red-flag warnings this summer, you still need that igniter," said Stuart Seto of the National Weather Service in Oxnard. "Basically, we've had less igniters in our area."
Los Angeles County Fire Inspector Rick Flores said the county "has been pretty lucky.... We've had little starts here and there, but we've put them out pretty quickly."
But strong Santa Ana winds generally begin developing in October and can last through December. In wet years, the hot, dry conditions are tempered by fall and winter rainstorms. But forecasters don't expect much of that this year.
"It's a race we run every fall: What comes first, the rains or the Santa Anas," said William Patzert, a climatologist for NASA's Jet Propulsion Laboratory. "The dice are loaded this year for Santa Anas … and who knows how intense or benign it will be."
Officials cited the Silverado Canyon fire in Orange County two weeks ago as an example of how a small fire can get out of hand. It was started by metal sheeting that a homeowner put up to protect a backyard vegetable garden from small animals. The sheeting essentially acted as a magnifying glass during the intense heat, sparking a fire that ran up the hill and grew to almost 1,000 acres.
Moisture levels in Southern California's brush and leaves are at critically low levels and that fueled the fire's spread, said George Ewan, a wildland fire defense planner for the Orange County Fire Authority.
"Even though the vegetation is alive, it'll burn like it's dead. All those hillsides would burn like it's covered with dead vegetation," he said.
Firefighters got some breaks that slowed the spread of the Silverado Canyon fire and prevented widespread destruction. The fire occurred during extremely hot temperatures, but the winds were relatively calm. The fire also moved away from homes and into the Cleveland National Forest.
A fire in the hills of Orange County has room to spread fast. The last major blaze was in 2008, when the Freeway Complex fire in Santa Ana Canyon burned more than 30,000 acres.
"So we've had plenty of chance for the vegetation to grow back and burn," Ewan said. "The first thing that grows back is grass and weeds ... you have what we call 'flashy fuels.' It grows fast, dries fast and burns fast."
It's already been an unprecedented year for fire officials across the state. Last week, more than 66,000 firefighters were battling 10 major California fires. Officials knew the year was going to be stressful when a major fire erupted in January in Humboldt County, one of the wettest regions in the state. Earlier this spring, a number of brush fires swept through San Diego County when a surprise wave of strong winds hit half a year earlier than expected.
"That peak period of time is now, and is still ahead of us," Berlant said. "The largest of the fires, the most destructive of the fires, typically occur in Southern California."
Times staff writer Veronica Rocha contributed to this report.