The National Weather Service San Francisco Bay Area is alerting locals to prepare for increased onshore winds, starting later today. According to forecast updates, areas such as the inland gaps and passes of the East Bay and the Delta Region could experience wind gusts ranging from 30 to 40 mph. This wind advisory emerges amidst concerns regarding fire weather conditions, especially considering the season's already dry nature. NWS Bay Area emphasized the potential severity of the gusts and their impact on fire weather concerns in a recent social media post.
⚠️Onshore flow increases later today leading to stronger winds. Winds will be strongest in the inland gaps/passes of the East Bay and the Delta Region. Wind gusts of 30-40 mph will be possible. Gusty winds will also increase fire weather concerns. #cawx pic.twitter.com/LDFFkiVQGU
— NWS Bay Area 🌉 (@NWSBayArea) July 20, 2025
The uptick in winds also increases the risk of wildfires in these areas. The East Bay Hills are particularly susceptible, and the expected winds coupled with low humidity levels reaching down to 25-40% have heightened this risk despite not being critical relative humidity values. As a statement acquired by the National Weather Service details, the building of an upper-level trough has contributed to the cooling trend but also "create increased fire weather concerns for the East Bay."
The cooling trend brings with it not just gusty winds, deeper marine layers, and coastal drizzle. Night and morning cloudiness are expected, with clearings in the afternoon, typical for coastal California summer. However, with an anomalously low upper-level trough lingering overhead, temperatures are predicted to remain below normal for the season, as the long-term forecast suggests. The interior warmth previously experienced due to the weakened upper-level ridge dissipates as the trough's presence becomes more pronounced.
As for marine conditions, the National Weather Service advises that from today through Friday, light to moderate northwest breezes will strengthen to more brisk winds. Mariners are cautioned to be wary of gusty conditions that could prove hazardous, particularly "each afternoon and evening through the Golden Gate, into the Delta and along the favored coastal jets off Pigeon Point and the Big Sur coastlines." While the winds are set to diminish before midweek, they are projected to quickly ramp back up, reinforcing the need for continued vigilance in fire-prone areas.
