Overview
- A first band of steady rain and high‑elevation snow is forecast to arrive Friday and peak that afternoon into the evening, with the steadiest rain focused on coastal ranges and the Sierra west slope.
- A second, colder wave is likely Sunday into Monday that will lower snow levels to around 5,500 feet and raise the chance of chain controls and travel delays over Sierra passes.
- Rain totals are expected to be beneficial not hazardous, with about 0.25–0.5 inch per round in the Sacramento Valley and roughly double to triple that on the Foothills and Sierra west slopes, making major flooding unlikely.
- Strong southwest winds are likely Friday with gusts over 40 mph in exposed gaps and very large offshore swells of 30–40 feet that could produce downed trees, scattered power outages, and hazardous coastal surf.
- Forecasters stress uncertainty about exact timing and intensity and describe this weekend as an opening act for the wet season, noting Scripps and longer‑range models point to a higher‑confidence wetter core in January–February.