Coastal flood advisory for the San Pablo Bay shore runs through Saturday evening

By The Downspout · Posted Oct 29, 2026 · 3 min read

The National Weather Service says high tides could put up to 1.9 feet of water over low-lying ground near the bay shore, including San Pablo Bay. The coastal flood advisory, listed for Sonoma, runs until 6 p.m. Saturday, October 31, 2026. It names no individual Sonoma towns or roads.

What the advisory covers

High tides are expected to flood low ground near the water. The National Weather Service, the federal weather forecaster, issued the alert. Its San Francisco Bay Area office wrote it.

The alert covers the bay shoreline of San Pablo Bay, San Francisco Bay and Monterey Bay. The alert text we read was the one the Weather Service lists for Sonoma. It names no Sonoma towns or roads. Its forecast zones include North Bay Interior Valleys, but its flooding language is limited to areas near shorelines and tidal waterways. Tidal waterways are creeks and channels that rise and fall with the tide.

The Weather Service says the more substantial impacts are expected along the Marin County bayshore.

State Route 37 is a 21-mile highway from Highway 101 in Novato to Highway 80 in Vallejo. It crosses the tidal marshes of San Pablo Bay through Marin, Sonoma, Napa and Solano counties. The State Coastal Conservancy calls these marshes the San Pablo Baylands. It says flooding closed the highway in 2017 and 2019. The advisory does not name State Route 37 or any road.

What happened

The advisory remains in effect until 6 p.m. Saturday, October 31, 2026. The Weather Service's home page says it was extended through Saturday. The home page rates the coastal flood risk as moderate, 3 on a scale of 5.

The alert says up to 1.9 feet of water above ground is possible in low-lying areas near shorelines and tidal waterways. It lists these effects: flooding of low-lying infrastructure, isolated road closures and coastal erosion.

The alert also gives high tide times for the San Francisco tide gauge, the instrument that measures tide height. These are San Francisco predictions, not San Pablo Bay readings. They are a different measure from the 1.9 feet of water over ground. Each is in feet above normal tide:

Thursday, October 29, 1:43 p.m.: 1.9 feet above normal.
Friday, October 30, 2:39 p.m.: 1.6 feet above normal.
Saturday, October 31, 3:44 p.m.: 1.1 feet above normal.

The alert says those predictions include up to 1.2 feet of storm surge, which the alert says adds to the normal tide. Where you are, high tide can come up to 90 minutes earlier or later than those times.

The Pacific Coast advisory is separate. The home page says it runs through Friday.

What it means for you

If you drive near the shore, the Weather Service says to allow extra time. Roads may close. Do not drive around barricades or through water of unknown depth.
If you own property near the water, the alert says to take the necessary actions to protect flood-prone property.
If you own a boat, the Weather Service home page suggests longer dock lines and making sure the boat has enough water under it.
If you are on a beach or the shore, the alert says rising tides bring water farther up the beach and can restrict your way out.
To check your area, the Weather Service points to tide predictions at tidesandcurrents.noaa.gov and updates at weather.gov/BayArea.

What happens next

The advisory ends at 6 p.m. Saturday, October 31, 2026, unless the Weather Service changes it. Check weather.gov/BayArea for updates.

Related: our post on king tides.

Where this came from

The National Weather Service San Francisco Bay Area alert issued at 4:23 a.m. Thursday, October 29, 2026, and the office's home page, both read October 29. Background on State Route 37 and the San Pablo Baylands comes from the State Coastal Conservancy and Caltrans pages listed below.

Sources

Checked 2026-10-29. Rules and programs change. If something here is out of date, the source above wins. Spot an error? See our corrections policy.