A potent cold front from the Gulf of Alaska headed into drought-stricken California on Tuesday, and forecasters predicted widespread rain, mountain snow, gusty winds and unusually low temperatures in much of the state.

With the calendar still saying autumn, winter storm warnings were set to go into effect in much of the Sierra Nevada by early afternoon and forecasters advised against mountain travel due to expected deteriorating conditions.

“Travel could be very difficult to impossible,” the National Weather Service said.

The California Highway Patrol office at Truckee, in the Sierra north of Lake Tahoe, said drivers should expect chain controls and delays due to the first significant snow of the season.

The weather service said the heaviest precipitation was expected in Northern California, with lighter totals across Southern California.

“While much needed, this precipitation will not make much of a dent in the extreme to exceptional drought that continues to plague much of California,” forecasters wrote.