SAN DIEGO — A massive aerial assault and a break in harsh winds helped firefighters make their first major progress against Southern California’s firestorm, raising evacuees’ hopes of returning home for good. But flames were still drawing perilously toward thousands of homes.

The hot, dry Santa Ana winds that have whipped the blazes into a destructive, indiscriminate fury since the weekend were expected to all but disappear today.

“That will certainly aid in firefighting efforts,” National Weather Service meteorologist Jamie Meier said.

The record high temperatures of recent days began succumbing to cooling sea breezes, and two fires that burned 21 homes in northern Los Angeles County were fully contained.

President Bush, who has declared a major disaster in a seven-county region, was scheduled to arrive in California today and to take an aerial tour of the burn areas, accompanied by Governor Arnold Schwarzenegger.

Losses total at least $1 billion in San Diego County alone, and include a third of the state’s avocado crop. The losses are half as high as those in Southern California’s 2003 fires, but are certain to rise.

The more hopeful news on the fire lines came a day after residents in some hard-hit San Diego County neighborhoods were allowed back to their streets, many lined with the wreckage of melted cars.

In upscale Rancho Bernardo, house after house had been reduced to a smoldering heap. Cheryl Monticello, 38 and eight months pregnant, knew what she would find when she came back yesterday because a city official warned her the house was lost. But she had to see it for herself.

“You really need to see it to know for sure,” Ms. Monticello said.

Only the white brick chimney and her daughter’s backyard slide had survived the inferno that bore down on her neighborhood Monday morning.