The Twilight Zone of San Francisco’s ongoing weird weather continues, as the National Weather Service [NWS] has issued a freeze warning and a frost advisory in the Bay Area through Tuesday despite the summer-like temperatures that have descended on the region for most of February.
Blustery, cool conditions will persist over the region with isolated to scattered showers/snow showers (higher elevations) possible along coastal areas this morning. Sky conditions will clear along with subsiding winds overnight with widespread freezing temperatures likely Tuesday morning. Cool unsettled weather conditions are then expected through the remainder of the week and potentially into early next week as well.
[The forecast] will bring an increase in cloud cover to inland areas and should limit widespread freezing temperatures. With that said, some of the coldest inland areas will still briefly cool into the upper 20s to lower 30s.
The forecast also calls for four to eight inches of snow around the Big Sur region. Closer to San Francisco, NWS followed up on the freeze warning with a frost advisory from midnight through 9 a.m. on Tuesday across all coastal area except San Francisco itself:
Wind speeds are expected to diminish by late Monday night and will set the stage for widespread freezing temperatures across inland areas from late tonight into Tuesday morning. In addition, frost is likely in coastal areas as temperatures drop to near freezing.
A frost advisory simply means that the formation of frost is likely overnight. Although NWS notes that “this condition is primarily significant during the growing season” and poses the greatest potential harm to agricultural interests, in urban environments it’s a reminder that very low temperatures can pose dangers to pets and to person’s without shelter for the night.
The Monday forecast for San Francisco calls for a sunny day and a clear night, with a high of 51 and a low of 38.