Overview
- A persistent upper‑level trough over the West Coast and strengthened onshore flow have deepened the marine layer, producing widespread low clouds and morning drizzle across coastal and many inland areas.
- Friday temperatures were several degrees below normal in large parts of the state, producing fall‑like highs in the Bay Area and Central Coast while inland valleys remained cooler than typical mid‑August readings.
- Isolated showers and brief thunderstorms are possible over mountains where small vorticity lobes give 15–30% convective chances in parts of San Luis Obispo and Santa Barbara Counties.
- The deeper marine layer raised low‑level humidity near the Timber Fire, improving conditions for firefighters and bringing air quality in the immediate area down to good‑to‑moderate levels.
- Forecast models show 500‑millibar heights rising and an upper‑level ridge rebuilding late this weekend into next week, which should gradually shrink the marine layer and return temperatures toward or above seasonal normals; Tropical Storm Lala in the Central Pacific remains a separate forecast concern for Hawaii.