Overview
- The subtropical moisture plume that soaked the North Bay is shifting south, bringing periods of moderate to heavy rain to the Bay Area and Central Coast through Monday and Tuesday.
- A second, comparable system arrives Wednesday night into Thursday, extending rain through Christmas with roughly 1–3 inches in valleys and 3–6 or more in mountains, and forecasters note additional waves may follow.
- Flood watches include the North Bay, much of Los Angeles County from Tuesday afternoon to Wednesday evening, and all of San Diego County from early Wednesday to early Thursday, where 2.5–4 inches are possible and burn‑scar areas face mud and debris‑flow danger.
- Gusts of 40–50 mph are expected broadly, with 60–80 mph possible along exposed coastlines and higher terrain, raising risks of downed trees, power outages and dangerous surf.
- Holiday travel disruptions are likely for drivers and fliers in California, while a separate New England system is set to bring light to moderate snow Tuesday into Tuesday night, generally 1–3 inches with 3–6 inches in northern high terrain.