The wildfires that exploded across Southern California this week were spread by Santa Ana winds, a dry-weather phenomenon that can produce gusts of up to 100 mph that often leave people gasping.
The devil's breath, as the condition is known, begins as a high-pressure system whose cool, sinking air sweeps across the Mojave Desert, then flows downward to the ocean.
The winds must squeeze through mountain passes and canyons, causing the air to heat and move faster -- commonly exceeding 40 mph as they burst out across coastal lowlands, meteorologists say.
On rare occasions, the winds briefly blow up to 100 mph, making the Santa Ana condition as powerful as a Stage 2 hurricane.
"The Santa Anas wouldn't be nearly so powerful if not for the dryness of the desert and the narrowness of the mountain passes," said James Murakami, a meteorologist at the University of California, Los Angeles.
The Santa Anas haven't blown at hurricane force in Orange County during this century. But in January 1946, winds of up to 60 mph devastated citrus crops around Southern California.
This latest episode began as a high-pressure system that drifted off the ocean into the Pacific Northwest, then headed south into Idaho and Nevada.