As of the Climate Prediction Center's October 8, 2026 ENSO discussion, an El Niño Advisory is in effect, and NOAA says a strong-to-very strong El Niño is likely through January–March 2027. NOAA is also careful to say that a stronger event makes El Niño-like impacts more likely, not guaranteed. El Niño winters have historically tilted Northern California toward wetter conditions, but individual seasons vary, and no outlook can tell you when or where a specific storm will hit. Watch the CPC seasonal outlooks and the National Weather Service Bay Area office for forecasts as the season unfolds.
For Marin homeowners, the practical takeaway is simple: you can't control the weather, but you can control how ready your house is when a big storm or a string of atmospheric rivers rolls through. Most of the water damage we see described by homeowners comes from a handful of predictable weak points: clogged drainage, overwhelmed crawlspaces, old supply lines, and roofs or windows that let wind-driven rain in. This checklist walks through them in the order we'd tackle them in October and November.
Marin County's AlertMarin system sends alerts by call, text or email for floods, evacuations and other emergencies at the addresses you add. You can add up to five Marin addresses (home, work, a child's school) and opt into flooding and weather alert groups. The county also recommends saving the AlertMarin number in your phone so alerts ring through Do Not Disturb.
Then look honestly at where your home sits. If you're in the Ross Valley along Corte Madera Creek (see our San Anselmo, Fairfax, Ross and Kentfield pages), near San Rafael Creek or the Canal (see San Rafael), along Novato Creek, or on bay-edge fill in Corte Madera, Larkspur or Greenbrae, your risk profile is different from a hillside home in Mill Valley. The Marin County Watershed Program is a good starting point for local flood information.
Water damage is often a drainage failure first. Before the first big storm:
Many Marin homes, especially older ones in the Ross Valley, San Rafael and Mill Valley, sit over crawlspaces. Grab a flashlight and look for standing water, water staining on the foundation, torn vapor barriers, or a musty smell. If you have a sump pump, test it by filling the pit with water, and think about backup power. Storms and power outages often arrive together.
Not all water damage comes from the sky. Rubber supply lines to toilets, sinks, dishwashers and washing machines can fail without warning. Braided stainless lines are an inexpensive upgrade. Equally important: find your main water shutoff now, make sure it turns, and show everyone in the household where it is. A burst pipe is far less damaging when someone can stop the water in two minutes instead of twenty. Our page on burst and leaking pipes covers what happens next.
Wind-driven rain finds the weak points: worn roof flashing, failed window seals, and door thresholds that face the prevailing storm direction. If your roof is older or you've had leaks before, schedule an inspection now, while contractors still have room in their calendars. Our sister site has a guide on roof inspections before the rain.
Take thirty minutes to read your homeowners policy. Many standard policies cover sudden and accidental water damage, like a burst pipe, but exclude flooding from outside water, which typically requires separate flood insurance. The federal flood insurance program at FloodSmart.gov explains how flood policies work. Flood policies often have a waiting period before coverage starts, so check the details now rather than when a storm is on the forecast. The California Department of Insurance publishes residential insurance guides, including a winter storm tips guide and a claims guide.
Walk through your home with your phone and video every room, including the crawlspace, garage and the contents of closets. Store it in the cloud. If you ever need to file a claim, "before" footage is extremely useful. The Department of Insurance's guides include a home inventory guide.
Not every Marin resident owns a single-family home. If you rent, tell your landlord or property manager about drainage problems, leaky windows or a musty crawlspace now, in writing, rather than in the middle of a storm. Renters insurance usually covers your belongings, not the building, so check what yours includes. In condos and townhomes, the HOA is typically responsible for roofs, exterior walls and common drainage, while you're responsible for your unit's interior and fixtures. Read your CC&Rs and the HOA's master policy so you know who to call when water comes through a shared wall or ceiling. Many Marin HOAs schedule roof and gutter maintenance in the fall, so ask whether that has happened this year.
Even well-prepared homes sometimes take on water. Stop the source if you safely can, stay away from water near electrical outlets or panels, take photos, and start drying fast. The longer materials stay wet, the more damage spreads and the greater the chance of mold. Our guide to the first 24 hours after water damage walks through the steps in order, and you can request help from an independent local provider any time.
No. NOAA says a strong El Niño makes typical El Niño impacts more likely but not guaranteed. Watch NWS forecasts as the season unfolds.
Standard homeowners policies often exclude flooding from outside water. Flood coverage is usually a separate policy; see FloodSmart.gov and your agent.
October and November, before the first major storms and before contractors' schedules fill up.
Generally the landlord handles the building and repairs; renters insurance may cover your belongings. Report problems in writing.
It depends on your CC&Rs and the HOA's master policy; the HOA often handles roofs and exteriors.
This article is general information, not legal, insurance or medical advice. Sources are linked in the text.