The National Weather Service has issued a frost advisory for the Bay Area from 4 a.m. to 9 a.m. Monday due to cool temperatures expected throughout the region.

Clear skies, calm winds and cool temperatures are expected to lead to patchy frost, and temperatures may drop between 32 and 35 degrees.

Alameda County and nine other Bay Area counties although temperatures in the Tri-Valley are expected to be well above freezing at the upper 40s.

Monday, the Tri-Valley is expected to be mostly sunny with highs in the lower 70s. North winds of 5 mph are anticipated.

— Bay City News Service