Timeline: Atmospheric river approaches Bay Area
Atmospheric river reaches Bay Area: What to expect
Strong southerly winds will be a major factor for much of the Bay Area when the storm arrives.
SAN FRANCISCO - An atmospheric river is headed for the Bay Area, bringing heavy rainfall and strong winds beginning late Wednesday and lasting through early Friday.
The storm system is expected to deepen as it slides down the West Coast, according to the National Weather Service.
What to expect
What we know:
Strong southerly winds will be a major factor for much of the region. In San Francisco and San Mateo counties, gusts could reach 50 to 60 mph from 10 p.m. Wednesday through 10 a.m. Thursday, prompting the National Weather Service to issue a high wind warning.
Forecasters said the coastal North Bay and Marin Hills could see gusts of 55 to 60 mph, with winds as strong as 70 mph possible along coastal ridges and higher elevations.
The storm is expected to produce widespread rainfall Wednesday night through Thursday, tapering off with light rain Friday.
Rainfall totals
Local perspective:
Forecast rainfall through early Friday:
- North Bay: 1.25 to 5 inches
- East Bay: 0.75 to 2.25 inches
- San Francisco Peninsula, Santa Cruz, and South Bay: 1.25 to 3.5 inches
A few thunderstorms are possible early Thursday.
Residents should expect a slow Thursday morning commute with ponding on roads, scattered debris, possible power outages, and downed trees, especially along the coast and in higher terrain.
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Storm timeline
Big picture view:
- Late Wednesday night–early Thursday: Storm system arrives; winds strengthen across the Bay Area.
- Thursday: Heaviest rainfall and strongest winds. Minor urban and small-stream flooding possible.
- Friday: Light rain continues before the system moves south.
Regional forecasts
North Bay
- Wednesday: Rain with possible thunderstorms and gusty winds.
- Thursday: Heaviest rainfall; best chance for thunderstorms and strong winds.
- Friday: Light rain.
Strong southerly winds with gusts up to 40 mph are expected, with locally stronger gusts along the coast, mountain ridges, and passes.
San Francisco
Rain is expected from Wednesday through Friday, with the heaviest falling Thursday. Beach hazards include waves up to 20 feet, creating a moderate risk of sneaker waves and strong currents.
Wednesday night into Thursday, strong winds may create hazardous driving conditions for large vehicles. Some tree damage is possible. Southerly winds may gust up to 40 mph, stronger along the coast.
Thunderstorms could bring lightning, gusty winds, and small hail.
Peninsula
Rain is forecast from Wednesday through Friday, with the heaviest on Thursday. Expect minor roadway ponding and flowing water in low-lying areas. Driving may be difficult for large vehicles.
East Bay
Rain arrives Wednesday through Friday, with the heaviest on Thursday. Strong winds are likely, and tree damage is possible Wednesday night into Thursday.
South Bay
Rain is expected from Wednesday through Friday, with heavier downpours Thursday. Strong southerly winds could gust up to 40 mph, with locally stronger gusts along ridgelines and mountain gaps.