Storm-prep guide · Updated October 19, 2026

El Niño storm prep for Sonoma County: a 2026–27 homeowner guide

A practical, sourced checklist for the 2026–27 El Niño winter in Sonoma County, from the Russian River to Petaluma. Jump to the printable checklist.

Sonoma County winters bring a different set of problems than Marin's. The Russian River rises and spreads into Guerneville, Monte Rio and Forestville. Creeks through Santa Rosa and the Petaluma River can climb fast. Hillsides below the 2017 and 2020 fire scars can send mud and debris downhill. This guide pulls the most useful prep steps into one place, with links to the official county, city and federal sources behind each one. Print the one-page checklist at the bottom, share it with neighbors, and work through it before the first big storm.

What NOAA is saying about this winter

NOAA's Climate Prediction Center (CPC) put an El Niño Advisory in effect, and its ENSO Diagnostic Discussion of October 8, 2026 says a strong-to-very strong El Niño is likely through January–March 2027, with better than an 83% chance. CPC is careful to add that, with an event this large, El Niño-type impacts are "larger, though not guaranteed." For Sonoma County, that means a wetter-than-normal winter is more likely, not certain. CPC's next update is due November 12, 2026.

The City of Sonoma opened its sandbag filling station early this year because of the outlook, while noting that El Niño "does not guarantee" flooding or severe storms (City of Sonoma).

Sign up for SoCoAlert first

SoCoAlert is Sonoma County's free emergency notification system for evacuation notices, shelter-in-place orders and flood warnings. You can sign up online with up to five addresses, or call (707) 565-1369 (SoCoEmergency). Add home, work and a parent's or child's address if they live in the county. During storms, also follow National Weather Service Bay Area forecasts. Sonoma Water runs a Flood Forecast Hotline at (707) 526-4768 (Sonoma Water).

Russian River and Guerneville: know your gauge numbers

The lower Russian River is the county's best-known flood zone. The flood of record at Guerneville came in February 1986, and in February 2019 the river crested there at 45.38 feet (NWS). The county estimated about $155 million in damage from that 2019 flood (Sonoma County).

The official forecasts come from the California Nevada River Forecast Center (CNRFC). At the Guerneville gauge, flood stage is 32 feet, and at 35 feet the CNRFC expects numerous businesses and homes in the lowest parts of river towns to flood. Upriver, flood stage at the Healdsburg gauge is 23 feet. Near Sebastopol, the Laguna de Santa Rosa gauge tracks the backwater that floods low parts of town.

What to do with the numbers:

• Find out at what Guerneville stage your street, driveway and crawlspace start to take water. Long-time neighbors often know.
• Decide in advance at what forecast stage you'll move cars, raise belongings and leave.
• Keep cars, papers and valuables above your own flood line before the crest, not during it. Roads into river towns can close.

Our sister site has a full Russian River flood stages guide.

Santa Rosa and Petaluma creeks

Away from the river, most flooding comes from creeks, storm drains and runoff that can't keep up with heavy rain.

• Santa Rosa: The city's Rain Ready page covers storm prep. Residents with a city ID can get sand and bags at 55 Stony Point Road during significant rain events.
• Petaluma: The Petaluma River and its tributaries have flooded parts of town before, including in 1982 and 2005. The city has updated flood maps and flood-management information.
• Everywhere: Keep the storm drain in front of your house clear of leaves, and don't park over it.

Look up your address on FEMA's Flood Map Service Center to see if you're in a mapped flood zone.

Burn scars and debris flows

Ground burned by wildfire absorbs less water, so hillsides below burn areas can produce faster runoff, mud and debris. The 2017 Tubbs Fire and the 2020 Glass Fire burned large areas around Santa Rosa and the Mayacamas foothills.

The City of Santa Rosa warns that flash flooding and debris flows become more likely during periods of intense rainfall (Rain Ready). It recommends:

• Identifying vulnerable areas on your property, such as slopes, drainage paths and low spots
• Using erosion control such as straw wattles and rock bags
• Clearing fire-related debris from creeks and drainages on your property
• Having an evacuation plan, and leaving early if told to

If you live below a hillside, take SoCoAlert warnings seriously even when your street isn't near a creek. Our sister site covers this in more depth: post-fire runoff and debris flows.

Sandbags

Sandbags redirect shallow, moving water. They don't make a home waterproof, and water can seep through them. Sonoma County lists sandbag assembly stations during weather events on its sandbag page, and several cities run their own:

• City of Sonoma: self-serve station at Depot Park, 270 First St. W, for city residents, opening October 20, 2026 (City of Sonoma).
• Santa Rosa: 55 Stony Point Road for residents with a city ID during significant rain events (Rain Ready).
• Sebastopol: see the city's sandbag notice.

Locations and hours change, so check the official page before you go, and bring a shovel. Stack bags across doorways, garage doors and the low point where water would enter, not against the wall all the way around the house. Our sister site's sandbag guide walks through filling and stacking.

Roofs and gutters

Most storm leaks start at the roof or in clogged gutters, not in a flood.

• Clean gutters and downspouts, then clean them again after the first big leaf drop. The City of Sonoma asks residents to collect leaves rather than blowing them into the street (City of Sonoma).
• Extend downspouts so water lands several feet from the foundation.
• From the ground, with binoculars if needed, look for lifted or missing shingles, cracked tiles and loose flashing at chimneys, vents and skylights.
• In the attic, look for stains, damp insulation or daylight around penetrations.
• If you rebuilt after a fire, have the first rainy season checked: new roofs and gutters can still have flashing or drainage problems that only show in heavy rain.

Don't get on a wet roof. If a leak starts, catch the water inside and call for a tarp. See El Niño roof prep for Sonoma County on Sonoma Roof Repair for the full roof checklist.

Sump pumps and crawlspaces

Many homes in Sebastopol, Forestville, Guerneville and other west county areas sit over crawlspaces that stay damp all winter.

• Test your sump pump by pouring a bucket of water into the pit. SoCoEmergency suggests a sump pump with a battery backup and installing check valves (SoCoEmergency).
• Make sure the discharge line runs away from the house and isn't clogged or buried.
• Look in the crawlspace before the season: standing water, wet insulation hanging down, or a musty smell are all signs to deal with now.
• Check foundation vents and the crawlspace access door so they close properly.

Insurance and paperwork

Standard homeowners policies don't cover flooding, and a flood policy typically takes up to 30 days to start (SoCoEmergency). Learn more at FloodSmart. Before the storms:

• Video every room, closet, the garage and the outside of the house.
• Save your policy number, your insurer's claim line and IDs in the cloud.
• Know where your main water shutoff and electrical panel are.
• Build or refresh a go-bag using Ready.gov's checklist, and plan for power outages (Ready.gov).

During the storm

• Follow SoCoAlert and NWS Bay Area updates.
• Never walk or drive through floodwater. Six inches of moving water can knock you down (SoCoEmergency).
• If you're trapped in a building, go to the highest level, but don't climb into a closed attic where rising water could trap you.
• Run generators outdoors only, away from windows and doors.
• Evacuate when told to. In an emergency, call 911.

After the storm: what to do first

1. Stay safe. Don't enter floodwater or a flooded room if the power may be on. If you can reach the panel from a dry spot, turn off power to wet areas.
2. Stop the source. For a pipe or appliance, close the main water valve. For a roof leak, catch the water and get a tarp up once it's safe.
3. Document everything. Photograph and video every wet area, the water line on walls, and damaged items before you move them.
4. Call your insurer and a restoration provider.
5. Dry fast. The EPA says drying water-damaged areas within 24 to 48 hours usually prevents mold growth (EPA).
6. Check for mold later. A musty smell or stains in the days after a storm mean moisture is still there. See our sister site's drying and mold timeline.
7. Hire carefully. Verify any contractor's license at CSLB. In a declared disaster area, contracting without a license is a felony (CSLB).

Storm risks by town

Every part of Sonoma County floods differently. Find your town for its local risks, sandbag sites and a direct line to a provider who works there.

Santa Rosa

The county's largest city. Hillside neighborhoods rebuilt after the 2017 Tubbs Fire and 2020 Glass Fire face post-fire runoff: the city's Rain Ready page warns that flash floods and debris flows are more likely during intense rain. Report creek debris to Stream Maintenance at (707) 543-3800 (after hours (707) 543-3805); the sewage emergency line is (707) 543-4200. Free sand and bags at 55 Stony Point Road during significant rain events, with an ID showing a city address.

Water damage in Santa Rosa · Roof repair · Mold removal · Santa Rosa storm runoff and creek flooding

Petaluma

The Petaluma River runs through downtown. A summary of the city's floodplain plan lists significant floods in 1982, 1983, 1986, 1995, 1996, 1998 and 2005 (Petaluma Wetlands Alliance). The city's flood projects include Payran Reach, Denman Reach and Capri Creek, and it updated its flood modeling in 2023 to account for sea-level rise (City of Petaluma). Projects reduce risk but don't eliminate it, so check your address on the city's maps.

Water damage in Petaluma · Roof repair · Mold removal · Petaluma River flood cleanup

Rohnert Park & Cotati

Flat Santa Rosa Plain towns away from the big rivers. Rohnert Park incorporated in 1962, so most homes date from the late 1950s on (City of Rohnert Park). Storm risks here are mostly water at garage and sliding doors, overflowing gutters, and aging water heaters and supply lines that fail in any season.

Water damage in Rohnert Park & Cotati · Roof repair · Mold removal

Windsor

Between Santa Rosa and Healdsburg on the Santa Rosa Plain. Storm problems usually come from gutters, drainage and doors rather than the river. The County lists the Town of Windsor Public Works Corporation Yard, 8400 Windsor Road, as a sandbag location (SoCoEmergency).

Water damage in Windsor · Roof repair · Mold removal

Healdsburg

The Russian River runs along the city's southern edge. Flood stage at the Healdsburg gauge is 23 feet; at the 29-foot major stage the CNRFC says homes, businesses and secondary roads in the lower sections of Healdsburg begin to flood (CNRFC). City sandbags: Abel De Luna Community Center, 1557 Healdsburg Ave. (SoCoEmergency).

Water damage in Healdsburg · Roof repair · Mold removal · Russian River flooding in Healdsburg

Sebastopol

On the edge of the Laguna de Santa Rosa, which backs up into low parts of town when the Russian River is high. In February 2025 Petaluma Avenue flooded near the Joe Rodota Trail and Morris Street closed (Sebastopol Times). Free sand and bags for residents behind the Youth Annex, 425 Morris Street, up to 25 bags each (City of Sebastopol). Shaded west county crawlspaces stay damp all winter.

Water damage in Sebastopol · Roof repair · Mold removal · Laguna flood cleanup in Sebastopol

Sonoma

The city opened its seasonal sandbag station early this year because of the El Niño outlook and especially urges residents whose properties have flooded before to prepare early (City of Sonoma). Self-serve sand at Depot Park, 270 First St. W, from October 20, 2026; free empty bags at City Hall, limit 10. Keep leaves out of gutters and storm drains.

Water damage in Sonoma · Roof repair · Mold removal

Glen Ellen & Kenwood

Unincorporated Sonoma Valley communities hit hard by the 2017 Nuns Fire; the Press Democrat reported about 183 homes destroyed in Glen Ellen and 140 in Kenwood (Press Democrat), so many homes are rebuilds on slopes that can shed water fast. Keep runoff away from crawlspace vents and garage doors. Repairs go through Permit Sonoma.

Water damage in Glen Ellen & Kenwood · Roof repair · Mold removal

Guerneville, Monte Rio & Rio Nido

The lower Russian River. Flood stage at Guerneville is 32 feet and the flood of record is 49.5 feet, set February 18, 1986 (CNRFC). In the February 2019 flood the river crested at 45.38 feet, Guerneville was reachable only by boat, and the NWS says Guerneville and Monte Rio saw roughly 2,000 properties with some flood damage (NWS). The County has listed a sandbag station at the Monte Rio Fire Department, 9870 Main St.

Water damage in Guerneville, Monte Rio & Rio Nido · Roof repair · Mold removal · River flood cleanup in Guerneville

Forestville

Mostly above the river, but the CNRFC says Mirabel Park and the Mirabel trailer park flood at 36 feet on the Guerneville gauge, and Mirabel Road at River Road floods at 37 feet (CNRFC). The County has listed Fire District Station 7, 6554 Mirabel Road, as a sandbag location. Up the hill, tree cover means clogged gutters, roof leaks and damp crawlspaces.

Water damage in Forestville · Roof repair · Mold removal · Flood cleanup in Forestville

Cloverdale

The county's northernmost city, on Highway 101 and the upper Russian River. Most storm damage comes from roofs, gutters and drainage. Check the County's sandbag page for current locations, and call early in a storm, since north county drive times run longer.

Water damage in Cloverdale · Roof repair · Mold removal

Our Sonoma County sites

• Sonoma County Water Damage: flood cleanup, water extraction and drying. See their El Niño flood prevention guide.
• Sonoma Roof Repair: leak repair, storm damage and tarping. See their El Niño roof prep guide.
• Sonoma Mold Removal: mold inspection and remediation after leaks and floods.

In Marin? See our Marin County El Niño storm prep guide.

Frequently asked questions

Print the checklist Call (628) 336-1777

This guide is general information, not legal, insurance or medical advice. Sources are linked in the text. North Bay Pros is a referral service and doesn't perform the work.