The National Weather Service provided a brief respite on Wednesday as temperatures began to climb, prompting public safety officials to urge caution against heat and fire danger. Meteorologist Lamont Bain noted that the most intense heat period is expected to shrink, with Friday's highs potentially dropping from the low 90s to the high 80s, offering some relief after Thursday's oven-like conditions.
On Thursday, temperatures are forecast to reach the high 90s and could exceed 100 degrees in far inland areas of Contra Costa and Alameda Counties, as well as the Santa Clara Valley and Eastern Hills. In the North Bay, including Napa and Santa Rosa, temperatures are expected to hit at least 97 degrees.
A heat advisory will be in effect from noon Thursday to 11 p.m. Friday, warning that sensitive individuals, especially those without effective cooling or adequate hydration, may be affected.
A red flag warning for fire danger persisted through Wednesday and will expire at 9 a.m. Thursday, with the East Bay Hills and North Bay Interior Mountains at greatest risk due to offshore winds gusting 35-40 mph overnight.
Meanwhile, a coastal flood advisory will begin Wednesday night along the North Bay ocean coast and Thursday along the San Francisco Bayshore, with waves expected up to 1.5 feet above ground level in low-lying areas. High tides near San Francisco will occur at 8:11 p.m.
Wednesday, 8:51 p.m. Thursday, and 9:34 p.m.
Friday, with flood advisories expiring Saturday. Bain explained that after Thursday's heat, an offshore jetstream flow compressing the marine layer will give way to an onshore flow, causing temperatures to drop significantly by Sunday, with the same areas that threatened 100 degrees on Thursday likely not reaching 85.
The marine layer is expected to return with a vengeance, providing gradual relief. On Wednesday, temperatures peaked in the mid-90s in the far inland East Bay and low 90s in Livermore and Pleasanton, while Morgan Hill and San Jose reached 90 and 89 degrees, respectively.
Closer to the water, Oakland and Alameda hit 80 degrees, San Mateo 77, and San Francisco 74. PG&E has indicated that shutoffs are possible during this period of heightened fire weather concerns, particularly in Sonoma, Napa, and other Northern California counties.