LOS ANGELES — Walls of wind-driven fire swept across Ventura County on Friday, forcing thousands of home evacuations, shutting down schools and offices and ravaging acres of woodland as firefighters struggled for a second day to bring an ominously early California wildfire under control.

There were no reports of injuries or homes destroyed as the heat abated and fierce winds began tapering off Friday evening. But the intensity and early arrival of the year’s first major wildfire — months before such fires normally break out, just a few weeks after the end of the rainy season — offered a worrisome sign of what appears to be a severe fire season on the horizon.

Firefighters were confronting a troubling combination of bad factors that the state escaped in recent years, namely tinderbox conditions created by record-low rainfalls and brisk and fast-switching winds known as Santa Anas, infamously dry and hot.

“It’s burning out of control,” said Bill Nash, a spokesman for the Ventura County Fire Department. “We are in a very serious situation. We are getting a wind shift right now.” He said firefighters were forced to repeatedly redeploy in response to dangerously moving winds.