Highway 37 Closes Both Ways Between Vallejo and Sears Point October 23 to 26 for El Niño Work

Caltrans will fully close State Route 37 in both directions between Mare Island in Vallejo and Sears Point from 10 p.m. Friday, October 23, to 5 a.m. Monday, October 26, 2026, to raise sections of the roadway ahead of El Niño storms. The closure covers the 10.4-mile stretch along the north edge of San Pablo Bay, and it is one of several closures Caltrans District 4 announced on October 13. The Caltrans release says all work is weather dependent and that more weeknight work may be needed.

The Closure Schedule

• Wednesday, October 21, and Thursday, October 22: westbound SR-37 closed nightly from 7 p.m. to 4 a.m.
• Friday, October 23, 10 p.m., to Monday, October 26, 5 a.m.: full closure of both directions between Mare Island and Sears Point. Crews demolish part of the median and install K-rail so both directions can share the westbound lanes, then work on the eastbound lanes.
• Friday, November 13, 10 p.m., to Sunday, November 15, 5 a.m.: overnight closures to remove the temporary barrier from the westbound side and install it on the eastbound side.

The section of SR-37 between Novato and Sears Point stays open, SFist reported.

Why Caltrans Is Doing It Now

Caltrans says crews are raising portions of the eastbound roadway by 3 feet to address flooding on the route, and are speeding up work that requires full closures because of the El Niño forecast. SFist reported that the largest piece of the job is a 1,300-foot section where concrete and asphalt will be poured. “This is an indication to me of the state-level urgency about El Niño,” Metropolitan Transportation Commission spokesperson John Goodwin told SFist. The state has allocated $100 million for Highway 37 work, two-thirds of it for a separate planned toll-lane project on the same stretch, according to SFist.

Detours

During the full closure, Caltrans is sending traffic around the closed stretch through Napa and Sonoma counties on SR-121, SR-12 and SR-29:

• Eastbound (toward Vallejo): exit onto northbound SR-121 at Sears Point, turn right onto SR-12 (Carneros Highway), then right onto SR-12/SR-29 and take the connector back to eastbound SR-37.
• Westbound (toward Novato): take the SR-37 off-ramp to SR-29 in Napa, continue north on SR-29 and SR-29/SR-12, turn left onto SR-12/SR-121 (Carneros Highway), stay left on SR-12/SR-121 (Fremont Drive), turn left onto SR-121 (Arnold Drive) and turn right onto westbound SR-37.

Caltrans says to expect significant delays and to follow posted detour signs. Live conditions are on Caltrans QuickMap.

What It Means for Trips From San Francisco

Drivers going from San Francisco to Sonoma or Napa on US-101 and SR-37 can still reach SR-121 at Sears Point, because the closed stretch begins east of that junction. Trips that use SR-37 between Marin or Sonoma and Vallejo, Mare Island or Interstate 80 are the ones that hit the closure; those drivers will be routed through the Carneros detour on the October 23 to 26 weekend.

For San Francisco’s own storm preparations, see our El Niño explainer. If you would rather not drive to wine country, our small-group wine country day trip leaves from San Francisco.

Photo: Sears Point and the Sonoma Mountains seen from westbound SR-37. Lithium6ion, public domain, via Wikimedia Commons.