Overview

• The Bay Area is transitioning from an unusually dry April to its first credible rain window of the spring season, expected Friday into Saturday.
• An upper-level low-pressure system spinning off the coast is forecast to lower temperatures by 10–15°F below seasonal norms and increase instability in the atmosphere.
• Rain chances are estimated at 30–45%, with most areas receiving under 0.1 inches, though up to 0.25 inches is possible in elevated regions south of the Golden Gate.
• Onshore winds are strengthening, with gusts of 30–35 mph expected through coastal gaps and ridgelines, contributing to cooler and cloudier conditions across the region.
• There is a small chance of isolated thunderstorms, with probabilities under 15%, and light snowfall is possible in the Sierra Nevada as colder air moves aloft.