Drivers were urged to bring tire chains when traveling in the San Bernardino Mountains.
Caltrans crews worked throughout the night and into the morning hours to clear a light dusting of snow from the 15 and 138 freeways in the Cajon Pass.
A winter weather advisory is scheduled to expire at 10 a.m. Thursday for areas of the Inland Empire above 2,500 feet.
In the mountains, a winter storm warning remained in effect until 10 p.m. , with additional snow accumulations of 5 to 9 inches above 3,500 feet, as well as localized amounts up to 16 inches, expected. Dense fog is also in the forecast.
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"Be prepared for significant reductions in visibility at times,'' the National Weather Service warned.
Heavy snow and gusty winds may also result in some downed tree limbs and power outages, the weather service said.
City News Service contributed to this report.