Storm Season
San Diego Storm Season Prep: What a Strong El Niño Means for Your Home
Where Things Stand — updated September 28, 2026
- NOAA's ENSO Alert System status is an El Niño Advisory. In its 10 September 2026 diagnostic discussion, the Climate Prediction Center said El Niño is strengthening, with a greater than 90% chance of a very strong event during autumn and winter 2026-27.
- The Climate Prediction Center's winter outlook puts above-normal precipitation across Southern California, with probabilities above 50% from December through April and frequent atmospheric river events expected.
- Flood insurance timing note. Authorisation for the National Flood Insurance Program was set to expire on 30 September 2026 pending Congressional reauthorisation. When authorisation lapses, the programme cannot issue new policies until it is renewed, though existing policies stay in force to their expiry date. If you are considering flood cover, check current availability with an agent or at FloodSmart.gov rather than assuming a policy can be written today.
This block is reviewed and updated through the season. Everything below it is written to stay accurate for the whole winter.
Please note: this is general information summarising third-party public sources, not professional advice for your property. Agee Restoration Services is not responsible for third-party content or for decisions made based on it. Full notice at the bottom of this page.
What El Niño actually is
El Niño is a recurring pattern of warmer-than-average sea surface temperatures in the central and eastern equatorial Pacific, paired with a shift in atmospheric circulation. It is a season-long climate pattern rather than a single weather event, so it does not arrive on a given Tuesday and it does not make landfall.
What it does is move the winter storm track. In a strong El Niño the subtropical jet stream tends to steer storms into Southern California that would otherwise pass to the north. The practical result for a San Diego homeowner is not one bad night. It is a season with more opportunities for water to find a way into the building.
That distinction matters for how you prepare. Getting ready for a single event is the wrong mental model. Getting the building ready to shed water repeatedly, over several months, is the right one.
What an atmospheric river is
Most of the serious rain Southern California receives in an El Niño winter arrives as atmospheric rivers — long, narrow corridors of concentrated water vapour moving in from the Pacific. They deliver a great deal of rain in a short window rather than spreading it out.
For a house, the difference between steady drizzle and an atmospheric river is whether your drainage can keep up. Gutters, downspouts, area drains and yard grading that cope fine with ordinary rain can be overwhelmed within an hour, and water that cannot drain away goes somewhere else — usually toward the foundation, the garage slab, or a below-grade room.
Local Specifics
Where Storm Water Actually Gets Into San Diego Homes
After enough of these jobs, the same handful of entry points come up again and again.
- Roof and flashing. Skylights, chimney flashing, and the seams around roof penetrations. A roof that sheds ordinary rain can leak under wind-driven rain hitting it sideways.
- Clogged gutters and downspouts. Water backs up under the roof edge and runs down inside the wall instead of away from the house. This is the single most preventable cause on the list.
- Grading that slopes toward the building. Common on the hillside lots in Spring Valley, La Mesa and parts of Poway, where runoff is already heading downhill toward the foundation.
- Garage slabs and below-grade rooms. Often the lowest opening in the building envelope, and frequently where the water heater and stored belongings are.
- Windows and door thresholds. Especially older coastal homes in La Jolla, Ocean Beach and Coronado where frames and seals have taken decades of salt air.
- Sewer and drain backups. Heavy rain can surcharge older lateral lines and root-intruded pipe. That is contaminated water and it is handled differently.
Know your flood zone before it rains
FEMA has designated parts of San Diego as Special Flood Hazard Areas, including areas of Mission Valley, Sorrento Valley and Southcrest. You can look up any address on FEMA's Flood Map Service Center.
Before the Rain
What To Do Now, While It's Still Dry
None of this requires a contractor. It is the list we wish every property had worked through before the first big storm.
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Clear the gutters, downspouts and area drains
Ready.gov lists keeping drains and gutters clear as a basic flood preparedness step, and it is the cheapest thing on this page. Check that downspouts actually discharge away from the foundation rather than beside it.
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Walk the perimeter and look at where water will go
Stand outside and follow the slope with your eyes. Anywhere the ground falls toward the building, or a planter or hardscape traps water against the wall, is a place to address before December.
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Check the roof, flashing and skylight seals
From the ground with binoculars, or with a roofer if the building is older. You are looking for lifted flashing, damaged seals and anything that has shifted since last winter.
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Move what matters off the floor
Ready.gov recommends moving valuables to higher levels. In practice that means documents, photographs and electronics out of garage floors, below-grade rooms and the bottom shelf of storage.
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Know where your water shutoff is, and that it turns
Not storm-specific, but the single most useful thing a homeowner can know. Find the main valve, confirm it moves, and make sure everyone in the house knows where it is.
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Sort out sandbags early if you are in a low spot
The City of San Diego makes sandbags available to residents at recreation centres during storm season, typically with a per-household limit and with sand not supplied. Locations and limits change each season, so check the City's Storm Preparedness page for the current arrangements rather than relying on last year's.
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Sign up for alerts
The National Weather Service San Diego office issues the local watches and warnings. Ready.gov recommends signing up for community warning systems and a NOAA Weather Radio.
If you want a second opinion on where your building is vulnerable, we will come and look. Call 619-399-0516 — the inspection is free and there is no pressure to sign anything.
The insurance gap most homeowners don't know about
This is the part worth reading twice, because it catches people every winter.
A standard homeowners policy does not cover flood. Ready.gov states it plainly: homeowner's insurance policies do not cover flooding. Flood cover is a separate product, generally through the National Flood Insurance Program or a private flood insurer.
And there is normally a waiting period. A new NFIP policy typically does not take effect for 30 calendar days. There are exceptions — cover required as a condition of a mortgage, certain flood map changes, and some post-wildfire situations — but the general rule means buying a policy when rain is already in the forecast is too late for that storm.
The practical takeaway: if flood cover is something you have been meaning to look at, the useful time to do it is well before the wet season, not during it. See the status block at the top of this page for the current situation with the programme's authorisation.
Worth being clear about the line here: we are a restoration contractor, not an insurance adviser. We can document damage thoroughly and explain what we found. Whether a particular loss is covered is between you and your insurer. Our guide to water damage and homeowners insurance covers the questions worth asking them.
During the Storm
Safety First, and It Isn't Close
Ready.gov's guidance on moving water is blunt, and it is worth repeating exactly: “Do not walk, swim or drive through flood waters. Turn Around. Don’t Drown!” They note that just six inches of moving water can knock you down, and one foot of moving water can sweep a vehicle away.
Inside the building, the hazard that gets underestimated is electrical. If water is near outlets, wiring or a panel, do not wade in to investigate. Cut power to the affected area only if you can do it from a dry position, and call an electrician if you cannot.
Do not go into an attic or crawlspace during a storm to chase a leak. Wet framing, poor footing and live wiring in a confined space is how people get badly hurt for the sake of a bucket.
If flooding is affecting the street or public drains, the City of San Diego asks residents to report it through the Get It Done app or by calling the City's storm line.
If Water Gets In
The First Hour Matters More Than The Next Day
- Stop the source if it is safe and it is something you control — a shutoff valve, a supply line, a window left open.
- Stay out of standing water near outlets, wiring or a panel. Electrical risk outranks water damage every time.
- Get photographs and video before anything is moved or cleaned up. This is the documentation your insurer will want and it cannot be recreated later.
- Move what can be moved out of the wet area — furniture, rugs, boxes, anything on the floor.
- Do not assume a wet wall is drying on its own. Moisture moves into cavities and under flooring where you cannot see it, and closed wall cavities hold it for a long time.
- Call a restoration contractor while it is still wet, not after it smells.
Our first 24 hours guide goes through this in more detail, including what to avoid doing.
When it stops being a mop-and-fan job
Plenty of small leaks genuinely are a towel and a fan. The situations where that is not enough, and where waiting makes it worse rather than better:
- Water has been under flooring, behind a wall or above a ceiling, where you cannot see or reach it
- The water came from a sewer line, a drain backup, or across contaminated ground — that is a different category of water and it is handled differently
- Materials are still reading wet after a couple of days, or a musty smell has started
- Insulation is wet. It holds water against framing and rarely recovers on its own
- You are going to file an insurance claim and need the damage properly documented
The EPA's guidance on moisture is the short version of why speed matters: mould grows on damp materials, and the way to prevent it is to dry things quickly rather than to treat it afterwards.
What we do in those situations is extract the standing water, dry the structure with monitoring rather than guesswork, handle mould remediation if it has already started, and rebuild whatever had to come out. One licensed contractor from the first call to the last coat of paint.
Sources
Where This Information Comes From
Every factual claim on this page comes from one of these. No statistics we cannot point at.
- NOAA Climate Prediction Center — ENSO Diagnostic Discussion
- NOAA Climate Prediction Center — Seasonal Outlooks
- Ready.gov — Floods
- FEMA — Flood Insurance
- FEMA FloodSmart — National Flood Insurance Program
- FEMA Flood Map Service Center — check your property's flood zone
- City of San Diego — Storm Preparedness
- National Weather Service — San Diego forecast office
- EPA — Mold and moisture guidance
Forecasts change. The seasonal outlook described at the top of this page reflects NOAA's published position as of September 28, 2026; check the Climate Prediction Center directly for the current discussion.
Important notice — please read.
This page is general information for San Diego County property owners. It is not professional, legal, insurance or engineering advice, and it is not a substitute for an assessment of your specific property.
The forecasts, safety guidance and programme details summarised here come from third-party public sources — including NOAA, FEMA, Ready.gov, the EPA, the National Weather Service and the City of San Diego — which are linked above so you can read them directly. Those organisations control that information and may update, change or correct it at any time. Agee Restoration Services does not control that content, does not continuously verify it, and does not endorse or take responsibility for material on any external website.
Weather and seasonal outlooks are forecasts, not guarantees. Conditions at your property may differ from anything described here.
To the fullest extent permitted by law, Agee Restoration Services accepts no responsibility or liability for any action taken, decision made, cost incurred or loss suffered in reliance on this page. For guidance specific to your property, consult the appropriate licensed professional, your insurer, or the relevant public agency.
In a life-threatening emergency, call 911. For a water, fire or mould restoration emergency at your property, call us on 619-399-0516.
Serving All of San Diego County
Agee Restoration Services is based in the South Bay and serves every community in San Diego County, from Chula Vista and Coronado to La Mesa, La Jolla, Carlsbad, and Poway.
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