After the storm: an hour-by-hour drying and mold timeline for Sonoma County homes

El Niño 2026–27 · Updated October 18, 2026

Companion guides: flood prevention · roof prep · drying and mold timeline · North Bay Pros storm prep

Why this winter

NOAA's Climate Prediction Center has an El Niño Advisory in effect. Its October 8, 2026 discussion says a strong-to-very strong El Niño is likely through January–March 2027 (better than an 83% chance), with impacts "larger, though not guaranteed." More rain means more chances for leaks, floods and damp crawlspaces, which is how most indoor mold starts. CPC's next update is November 12, 2026.

The rule that drives everything

The EPA says that if wet materials are dried within 24 to 48 hours, in most cases mold won't grow (EPA). CDPH adds that porous materials that stay wet for more than a day or two may need removal even if they don't look moldy yet (CDPH). Every step below is about beating that clock.

Hour 0 to 1: safety

• If water is near outlets, cords or appliances, don't enter. Shut off power at the panel only if you can reach it from a dry spot.
• Stop the source if you can: shut the main water valve for a plumbing leak; contain roof drips with buckets.
• If floodwater is rising, follow evacuation orders. Sign up for SoCoAlert before storms.
• If you run a generator, keep it outdoors, at least 20 feet from windows, doors and attached garages (Ready.gov).

Hours 1 to 6: document and remove water

• Photograph and video every room, the water line and damaged items before moving things.
• Call your insurer to open a claim, and a water damage provider (Sonoma County Water Damage).
• Remove standing water with a wet vac or pumps. Move furniture, rugs and boxes out of wet areas; prop furniture legs on blocks.

Hours 6 to 24: open up and get air moving

• Pull up wet area rugs and carpet pad. Open cabinet doors, closets and drawers.
• Remove baseboards in wet rooms so walls can breathe.
• Start fans and dehumidifiers once power is safe. Keep windows closed if it's raining and the dehumidifier is running; open them when it's dry outside.
• Floodwater from a river or creek, or sewage, is contaminated. The EPA recommends professionals experienced with contaminated water (EPA). Soaked drywall, insulation and carpet usually come out.

Hours 24 to 48: the decision window

• Check moisture in walls, floors and cabinets (a provider's meters are best).
• Porous materials that are still saturated are candidates for removal. CDPH says porous materials such as drywall, ceiling tiles, drapes and upholstered furniture usually can't be effectively cleaned of mold.
• Don't close up walls or install new flooring yet.

Days 3 to 7: dry, verify, clean

• Keep drying equipment running around the clock.
• Scrub hard surfaces with detergent and water and dry completely (EPA). CDPH doesn't recommend bleach.
• Bag moldy porous materials and dispose of them as normal trash; CDPH says moldy material doesn't need to be treated as hazardous waste.
• Don't run your HVAC system if you suspect it's contaminated (EPA).

Weeks 2 to 4: rebuild only when dry

• Rebuild after materials are confirmed dry. If mold grew, have it remediated before closing up. See mold remediation.
• Hire carefully: verify licenses on CSLB, and pay no more than 10% or $1,000 down, whichever is less (CSLB).

The rest of the winter

• Watch for musty smells, new stains or peeling paint.
• Keep indoor humidity below 60 percent, ideally 30 to 50 percent (EPA).
• Check the crawlspace after big storms. See crawlspace moisture in Sonoma County.

Before the next storm

Two companion guides cover prevention: El Niño flood prevention for Sonoma County homes and El Niño roof prep.

Sources

• NOAA CPC: ENSO Diagnostic Discussion, Oct 8, 2026
• EPA: A Brief Guide to Mold, Moisture and Your Home
• EPA: Mold cleanup in your home
• CDPH: Frequently asked questions about mold
• SoCoAlert sign-up
• Ready.gov: Power outages
• CSLB: license check
• CSLB: disaster information

Sources checked October 18, 2026.

Frequently asked questions

This page is general information, not legal, insurance or medical advice. Sources are linked in the text. Sonoma Mold Removal is a referral service and doesn't perform the work.