Forecasters in California are using some of their strongest language to warn that windy conditions may help fires spread this week.

Los Angeles, Ventura counties and Santa Barbara counties face especially high risks of wildfires as tens of thousands of residents face possible power shutoffs — with forecasters announcing a rare weather advisory that's typically issued only once every few years,

Wind gusts topping 70 mph in the San Gabriel Mountains are providing a taste of the conditions that are expected to continue into Thursday.

A very strong, widespread and long-duration Santa Ana wind event will bring extreme fire weather conditions to many areas of Southern California, but particularly Los Angeles and Ventura counties into Thursday.