No new major fires had broken out by Sunday morning as fire crews inched closer to getting some of the largest blazes surrounded, according to the state Office of Emergency Services.
But a "red flag warning" -- meaning the most extreme fire danger -- was still in effect for Northern California until 5 a.m. Monday. And the coming days and months are expected to bring little relief.
Forecasters predicted more thunderstorms and dry lightning through the weekend similar to the ones that ignited hundreds of fires a week ago. Meanwhile, a U.S. Forest Service report said the weather would get even drier and hotter as fire season headed toward its traditional peak in late July and August.
Lower-than-average rainfall and record levels of vegetation parched by a spring drought likely mean a long, fiery summer throughout Northern California, according to the Forest Service's state fire outlook released last week.
Already the fires now burning will take weeks to months to fully bring under control, the report said.
Those blazes were mostly sparked by lightning storms that were unusually intense for so early in the season. But summer storms would likely grow even more fierce, according to the Forest Service.
"Our most widespread and/or critical lightning events often occur in late July or August, and we have no reason to deviate from that," the agency's report said.
The blazes have scorched more than 556 square miles and destroyed more than 50 buildings, said state emergency services spokesman Gregory Renick.
Air quality districts from Bakersfield to Redding issued health advisories through the weekend, urging residents to stay indoors to limit their exposure to the smoky air.
Air pollution readings in Northern California are two to 10 times the federal standard for clean air, said Dimitri Stanich, spokesman for the California Air Resources Board.
On Saturday, President Bush issued an emergency declaration for California and ordered federal agencies to assist in firefighting efforts in Butte, Mendocino, Monterey, Santa Clara, Santa Cruz, Shasta, and Trinity.
But California officials said the federal declaration doesn't go far enough. State and local governments also need federal financing to cover their "extraordinary costs in fighting these fires," said Henry Renteria, director of the state Office of Emergency Services.
Federal aid now includes four Marine Corps helicopters, remote sensing of the fires by NASA, federal firefighters, and the activation of the Federal Emergency Management Agency.
More than 18,000 firefighters, nearly 1,700 fire engines and bulldozers, and more than 80 helicopters and aircraft were fighting more than 1,000 active fires Sunday, Renick said.
