Bitter colds have the Silicon Valley and neighboring Californians hugging their heaters this weekend as the National Weather Service (NWS) San Francisco, CA, extends a frost advisory amidst an unseasonably chilly April. The advisory warns of temperatures set to plummet overnight, bringing frost hazards to local vegetation and potential pipe bursts. Areas to watch include much of Santa Clara Valley, the Santa Cruz Mountains, and the Carmel Valley, with residents urged to protect the four "Ps" — people, pets, plants, and pipes.

According to a forecast discussion released by the NWS, a dry spell has landed in the region under clear skies, allotting cold mornings and patchy fog expected through the weekend. "The rain has ended, winds have calmed, and skies have cleared overnight," states the National Weather Service San Francisco, CA, promoting quick morning temperature recoveries under sunny conditions. However, afternoon temps will hover in the chilly upper 50s. A warming trend is on the horizon next week as temperatures are predicted to swing from today's 10 degrees below normal to a balmy 10+ degrees above average. San Jose might even hit the elusive 80-degree mark, a warmth not felt since last November.

Aviators and sailors take note; the weather service says VFR conditions will hold steady through early afternoon before a weak frontal system introduces MVFR ceiling levels by evening. Post-frontal cloud coverage will likely linger into Sunday morning. Marine conditions are equally subdued, with a weak upper low from the Pacific Northwest expected to stir up stronger northwest winds by Sunday afternoon going into Monday.

While no heat advisory is yet in place, the agency is not ruling out the possibility as the week progresses and temps soar. The sudden shift is notable, marking a distinct pattern shift from a deep trough to a persistent ridge, a reminder of California's penchant for weather whimsy. On the waters, calm sails now, but swells and breezy conditions await seafarers by week's end, so best to keep a watchful eye on the forecast and enjoy the calm while it lasts.