SAN FRANCISCO — People in some parts of the San Francisco Bay area woke Saturday morning to something Saturday they're not quite accustomed to — frost on their windshields.

The National Weather Service says temperatures across the region dropped down into the upper 20s late Friday and early Saturday.

Forecasters say parts of the North Bay and East Bay saw some of the colder temperatures in the area, with the temperature in Angwin — a tiny community in Napa County — hitting a low of 23 degrees, while Clayton — in Contra Costa County — saw a low of 24 degrees

In San Francisco, the overnight dropped to 33, but the high Saturday is expected to only rise to about 48 degrees.

With another cold night in the forecast, fans heading to the 5 p.m. playoff game between the 49ers and Green Bay Packers are being advised to bundle up.