A rare climate setup is taking shape in the Pacific. If you own a home or manage a building in the San Gabriel Valley, Inland Empire, or Orange County, it is worth looking at your plumbing now — not after the first big storm.
What NOAA is saying about this winter
As of July 9, 2026, NOAA’s Climate Prediction Center has an El Niño Advisory in place. Forecasters say El Niño is already underway, still strengthening, and has about a 97% chance of lasting through early spring 2027.
The same July discussion is unusually clear on strength: there is an 81% chance of a “very strong” El Niño in the October–December window — ranking among the largest events since 1950. In common use, that “very strong” tier (around +2.0°C or higher on the Niño index) is what people mean by super El Niño.
A few caveats matter:
- El Niño is extremely likely. Flooding is never guaranteed.
- A strong Pacific signal raises the odds of a wet Southern California winter. It does not force every storm onto Pasadena or Rancho Cucamonga.
- Super El Niño years can still underdeliver rain. The very strong winter of 2015–16 was cooler and drier than many expected in southern California — prepare for odds, not promises.
Still, when NOAA’s base case is a top-tier El Niño, prep is cheap insurance compared with a flooded unit or a failed sewer line.
What past “super” winters did to Southern California
1997–98 — the wet analog people still cite
- Downtown Los Angeles saw about 13.7 inches of rain in February 1998 alone — roughly a normal year’s rain in one month, and the wettest February on more than a century of local records (NASA JPL climatologist Bill Patzert, via the LA Times).
- Parts of south Orange County got more than 7 inches in a single day earlier that season. Mobile home parks flooded; mudslides and blocked roads followed.
- Statewide damage reached the hundreds of millions, with 17 storm-related deaths and more than half a billion dollars in California damages reported at the time.
Climatology — and the dry super-year caution
Golden Gate Weather Services’ El Niño catalog shows that very strong events average about 155% of normal winter rain across California’s South Coast region (the coastal basin covering much of greater Los Angeles and Orange County). That is an average of a small sample, not a forecast — but it explains why plumbers and property managers pay attention. The 2015–16 counterexample still stands: ocean warmth ran hot, and local February rain in L.A. was under an inch.
How heavy rain seasons hit plumbing systems
When multi-day atmospheric rivers soak clay, asphalt, and fill, buried systems take the stress in five predictable ways.
1. Sewer laterals and mains back up
Stormwater can slip into cracked joints, open cleanouts, and root-broken laterals. Lines surcharge, and sewage can push into the lowest fixture — a floor drain, basement bath, or first-floor tub. Older San Gabriel Valley homes on clay or cast iron are especially vulnerable: roots expand as soils stay wet, turning a summer “slow” into a full backup. If drains gurgle or toilets bubble when it rains hard, treat that as a warning. Professional drain cleaning or a camera inspection often finds the restriction before peak season.
2. Storm drains and rain leaders clog first
Leaves, mulch, and dirt sit all summer. The first real wipeout of the rainy season moves that material at once. Backed-up downspouts and yard inlets push water under doors, into crawl spaces, or against foundations; commercial sites see the same at parking-lot inlets. Clearing them in October beats pumping a suite in January. Start with our rain-drain cleaning tips.
3. Sump pumps fail the first week they matter
Basements, crawl spaces, elevator pits, and low mechanical rooms lean on sump pumps that may have sat quiet for years. Float switches stick, motors seize, check valves corrode, battery backups die. Before rainy season, clear the pit, confirm the discharge line is intact, and verify backup power. See our sump pump maintenance guide and sump pump service page.
4. Saturated soil moves buried pipe
Wet clay expands and fill can shift. Slight movement can open joints on older laterals or aggravate a hairline slab leak — sometimes a wet yard spot or a creeping water bill rather than a gusher. A sewer camera inspection is the clean way to diagnose before digging; sewer line repair (including trenchless options when the site fits) is usually better than guessing.
5. Pre-rain jetting restores full pipe diameter
Light snaking punches a hole through a soft clog. It will not peel grease and root mass from a commercial kitchen main. Many buildings benefit from a heavy clean before a high-odds wet winter. Our comparison of hydro jetting vs. snaking covers where each tool belongs.
Prep checklist for the next few months
Homes
- Clear gutters and downspouts.
- Check exterior cleanouts for standing water.
- Run lowest drains hard and listen for gurgles or backups.
- Test the sump with a bucket of water; confirm discharge runs away from the foundation.
- Document slow drains now so you can still book non-emergency service.
Businesses and multi-unit buildings
- Clean parking-lot storm drains before the first atmospheric river.
- Camera and jet kitchen or grease-bearing lines if service is overdue.
- Confirm free roof drains and overflow scuppers.
- Confirm after-hours emergency plumber contact and gate access so a 2 a.m. backup does not become a multi-suite flood.
Bottom line
NOAA’s July 2026 outlook is one of the clearest El Niño strength signals in years: El Niño is here, expected to intensify, and a very strong / super-class event is the official base case for peak season, with roughly four-in-five odds in the October–December window. That tilts Southern California toward a wetter winter on average — and plumbing systems fail at the edges of capacity, not in the middle of a dry July.
You cannot move the Pacific Ocean. You can clear a rain inlet, service a sump, and free a brittle sewer line before the storm lines form.
If you need help with drains, sewers, sump pumps, or storm prep in the San Gabriel Valley and surrounding Southern California cities, call Western Rooter & Plumbing at (626) 448-6455 or schedule service online through our website.
