The Bay Area is in for a weather shift as the high pressure that brought a burst of early summer heat is now being edged out, heralding the start of cooler temperatures that will dip below normal early in the week. Coastal areas are particularly affected, with highs ranging from the mid-50s to the low 70s, though those traveling inland can expect slightly warmer climates, according to the National Weather Service San Francisco.
Despite the warm spell's conclusion, specific sectors like the North Bay and Central Coast will observe high temperatures close to the seasonal average in the 80s. At the same time, the interior locales aren't slated for a significant drop-off. The cooling is attributed to an upper-level trough deepening to the northwest, coupled with a cutoff low, which had been lingering west of Baja California, now inching northward and eastward, the two systems together impinging on our region's grasp on the high pressure that formerly held sway.
Looking ahead, the National Weather Service San Francisco projects more seasonal weather toward the mid to late week, with the possibility of a slight warm-up arriving by the weekend. Meanwhile, the marine layer will return Sunday night into Monday morning. A trough that moved into Northern California on Sunday is poised to transform into a cutoff low by late Sunday into early Monday, shifting southward along the California coast before reaching Southern California by Tuesday.
For mariners, this change in weather means a continuation of strong to gale-force gusts that will batter the outer waters until early this week. Those heading near Point Arena to Point Reyes should beware of storm forces. "Rough seas continue over the outer waters with significant wave heights building to 10 to 15 feet across the southern outer waters and up to 22 feet across the northern outer waters Sunday evening into Monday morning," the National Weather Service warned. Winds are anticipated to mellow by Tuesday, but sizable waves could persist through the end of the week.
The aviation forecast, citing potential complications at local airports, predicts that IFR to MVFR ceilings might develop along the coast, casting a slight uncertainty over the operations at SFO and OAK airports. Currently measuring roughly 1000 to 1500 feet deep, the marine layer is expected to contribute to stratus rather than fog formation this morning. SFO could see temporary IFR ceilings early on, but visibility is predicted to clear up by late morning, with a return to MVFR conditions forecast for tomorrow evening.
