SANTA ROSA, Calif. — It looked like a blizzard of red embers had slammed into the suburban home of Bruce and Lisa Coats.

Mr. Coats recounted on Monday how he used his garden hose to spray his home down in hopes of saving it. Then he went to his neighbors’ homes and tried the same thing. It was futile.

The combination of wind and fire was unstoppable. Coffey Park, a subdivision of hundreds of homes in Santa Rosa, an hour north of San Francisco, burned to the ground.

“It looks like a bomb went off,” said Ms. Coats, an accounts assistant at a retirement home.

“A nuke bomb,” said her husband, a soils expert.