Los Angeles County · Storm season 2026–27
El Niño 2026–27: LA Mold and Water Damage Prep Checklist
NOAA gives a better than 90% chance of a very strong El Niño this winter, with above-normal Southern California rain favored and a likely peak in December and January. The best mold prevention is keeping water out: check the roof, clear gutters, fix grading, and ready crawl spaces and sump pumps before the first big storm.
- Emergency24/7 response
- CoverageAll of Los Angeles County
- PricingQuote before any work starts
- StandardANSI/IICRC S520
- Call(213) 659-0672
The forecast
What does the 2026–27 El Niño forecast mean for Los Angeles?
As reported on October 7, 2026, NOAA gives a better than 90% chance of a very strong El Niño. Above-normal rain is favored for Southern California, with the strongest influence likely in December and January and effects lasting into spring 2027. Favored is not guaranteed, but the odds point to a wetter winter than usual.
Los Angeles normally gets about 14 inches of rain a year, and most of it falls between November and March in a few large storms. After a long dry season, roofs, gutters and drains get tested all at once. Mold calls usually follow storms by two to six weeks, once water has soaked into walls, ceilings and subfloors.
Step 1: Roof
How do I check my roof before El Niño storms?
Most storm mold starts at the roof. Look from the ground with binoculars, or hire a roofer for steep roofs. Roofers book up fast once the rain starts, so October and November are the time to schedule.
- Shingles and tiles: look for missing, cracked or slipped pieces, especially on the side that faces incoming storms.
- Flashing: check the metal around chimneys, vents, skylights and wall joints for gaps or lifted edges.
- Flat roofs: common on older LA apartments and mid-century homes. Look for ponding, blisters and cracked seams.
- Attic: on a sunny day, look for daylight through the roof deck, and for old stains or dark spots on the wood that mark past leaks.
- Fire areas: homes near the 2025 burn areas may have heat or ember damage that has not leaked yet. Have them checked.
Step 2: Gutters and grading
Where should rainwater go around my house?
Away from the foundation. Every gallon that lands near the walls is a gallon that can end up in a crawl space, under a slab or through a wall. Gutters, downspouts and the slope of the ground do this work, and most of the fixes are cheap.
- Clean gutters of leaves, ash and debris, and run a hose to confirm water flows to the downspouts.
- Extend downspouts so they discharge several feet from the house, not into a planter against the wall.
- Check grading: soil and paving should slope away from the house. Low spots next to the foundation collect water.
- Clear drains: area drains, patio drains and driveway drains clog over the dry months. Flush them now.
- Retaining walls: on hillside lots, make sure weep holes and drain pipes at the base are open.
- Hillside and burn-area runoff: if water and debris come downhill toward your home, talk to a contractor about diverting it before the rain.
Step 3: Under the house
How do I get a crawl space and sump pump ready for heavy rain?
Raised-foundation homes in the hills, the Eastside and Pasadena take most of their storm water from below. A crawl space that stays wet for weeks after a storm is one of the most common sources of hidden mold we see. Check it while it is still dry so you have a baseline.
- Vapor barrier: the plastic sheet on the ground should cover the soil fully, without tears or gaps.
- Vents: foundation vents should be open and screened, not blocked by soil, plants or storage.
- Old water lines: stains or silt lines on the foundation walls show where water collected last year.
- Wood: look for dark spots or fuzzy growth on joists and subfloor.
- Sump pump: pour a bucket of water into the pit and confirm the pump turns on and drains outside. Check the discharge line is clear.
- Power: storms knock out power. A battery backup or a plan for a portable pump keeps the sump working.
Already seeing growth under the house? Our page on crawl space mold removal explains what the work involves and why access affects price.
Step 4: Inside
What indoor checks help prevent storm mold?
- Windows and doors: replace cracked caulk and worn weatherstripping, and clear the weep holes at the bottom of sliding door and window tracks.
- Ceilings: photograph any existing stains so you can tell new leaks from old ones.
- Main water shutoff: know where it is and make sure it turns.
- Garages and basements: move boxes, papers and anything cardboard off the floor and onto shelves.
- Supplies: keep towels, a wet vacuum, a tarp, buckets and at least one fan on hand. Dehumidifiers sell out after big storms.
Take your insurance baseline photos now
Walk through the house and take dated photos and video of every room, the roof, the attic and the crawl space. Most homeowners policies cover mold only when it follows a sudden and accidental water event, often with a low mold sublimit, and long-term seepage is usually excluded. Before-and-after photos help show that the damage came from a specific storm. Read your policy now, and see our guide on whether insurance covers mold in California.
Step 5: Storm watch
What should I do the day before a big storm?
- Clear gutters and drains again. One windy day can refill them with leaves.
- Test the sump pump and charge any battery backup.
- Close and latch windows, and roll towels along any sliding door track that has leaked before.
- Lift valuables off garage and basement floors.
- Save the numbers: your insurer, a roofer, a plumber, and our 24/7 line at (213) 659-0672.
If water does get in, the clock starts. The EPA advises drying wet materials within 24 to 48 hours to prevent mold. Follow our after-storm 48-hour checklist.
Timeline and cost
When should each prep task happen?
| When | What to do |
|---|---|
| October to November 2026 | Roof inspection and repairs, gutter cleaning, grading and downspouts, crawl space check, sump test, baseline photos |
| Before each storm | Clear gutters and drains, test the sump, lift items off floors |
| During the storm | Check the attic, ceilings, windows and crawl space access for drips if it is safe |
| Within 48 hours after | Dry anything wet, photograph damage, call your insurer |
| Two to six weeks after | Watch for musty smells, new stains or peeling paint |
| Spring 2027 | Recheck the roof, crawl space and drains after the season |
Prep is cheap compared with what comes after a missed leak. A clogged gutter costs a morning. Mold that spreads through a wall or crawl space typically lands in the ranges below.
| Service | Typical LA range |
|---|---|
| Visual inspection with moisture mapping | $250–$500 |
| Small remediation (under 10 sq ft, one room) | $500–$1,500 |
| Typical residential remediation (bathroom, closet, crawl space section) | $1,500–$6,000 |
| Large, whole-house or structural | $10,000–$30,000+ |
Typical industry ranges for the Los Angeles area. Your written quote depends on the size, access and materials involved.
Renters
What if I rent?
Roofs, gutters, drainage and plumbing are generally the landlord’s responsibility under California habitability law. Before the storms, tell your landlord in writing about any old leaks, stains or windows that let water in, and keep a copy. If a leak is not fixed, the city or county can inspect for free. See which agency handles mold complaints in your city. This isn’t legal advice; contact Bet Tzedek or a tenant lawyer for help with your situation.
For why some homes take on more water than others, read why LA homes get mold, and for damage that has already happened, see mold remediation after water damage.
FAQ
El Niño and storm prep questions
Is a strong El Niño expected in Los Angeles this winter?
Yes, it is likely. As of October 2026, NOAA gives a better than 90% chance of a very strong El Niño, with above-normal Southern California rain favored. The strongest influence is likely in December and January, with effects lasting into spring 2027.
When should I prepare my house for El Niño?
October and November, before the rainy season gets going. Roofers and contractors book up quickly once storms start, and it is much easier to inspect a roof, a crawl space or a sump pump while everything is still dry.
What is the most important storm prep to prevent mold?
Keeping water out of the house. Start with the roof and flashing, then clean gutters, extend downspouts away from the foundation, and make sure the ground slopes away from the walls. Most storm mold starts with a roof leak or water pooling against the foundation.
How do I know if my crawl space floods?
Look for silt lines or stains on the foundation walls, puddles or damp soil, and dark spots on the wood. Check it before the season and again a day or two after a big storm. Water that stays for days needs drainage work or a sump pump.
Does homeowners insurance cover storm damage and mold?
It depends on the policy. Most cover mold only when it follows a sudden and accidental water event, often with a low mold sublimit, and long-term seepage is usually excluded. Read your policy before the storms and take dated photos of your home as a baseline.
How long after a storm can mold grow?
The EPA advises drying wet materials within 24 to 48 hours to prevent mold growth. Visible mold usually shows up two to six weeks after a storm leak, often after it has already spread inside a wall or ceiling.
Do Santa Ana winds cause mold?
No. Santa Ana winds are hot and dry, so they help materials dry out. They can, however, damage roofs and fill gutters with debris, which makes the next storm more likely to leak. Check the roof and gutters after a wind event.
More seasonal guides are in our Los Angeles mold and climate hub.
Sources
- NOAA El Niño outlook as reported by Claims Journal and Insurance Journal, October 7, 2026
- EPA, mold and moisture guidance: epa.gov/mold
- National Weather Service, Los Angeles and Oxnard office
- LA Housing Department: housing.lacity.gov
- ANSI/IICRC S500 (water damage) and S520 (mold remediation) standards
Last updated October 2026. We will refresh this page after major storms this season.
Water getting in, or worried it will?
We respond 24/7 across Los Angeles County, find where the water is going, and give you a written quote before any work. Call (213) 659-0672.