How to Prepare Your Hillside for a Historic El Nino Winter

On September 21, 2026, Governor Newsom declared a state of emergency to mobilize California's resources ahead of what NOAA's Climate Prediction Center is now calling a potentially historic El Nino. The latest CPC update puts the odds of a very strong event at greater than 90 percent for fall and winter 2026-27, with a 75 percent chance it ends up stronger than any El Nino on record dating back to 1950. Conditions are expected to persist into spring 2027.

Most of the preparation advice circulating right now is about people. Emergency kits, evacuation routes, sandbags. All worth doing. But there's a piece of most properties that doesn't make it onto those lists, and it's often the first thing to fail once the rain actually starts: the hillside.

Here's what a historic El Nino means for slopes specifically, and what to actually do about it before the first storm.

What a Historic El Nino Means for Your Property

A strong El Nino shifts more than just rainfall totals. Climate scientists tracking this year's event have flagged specific risks worth knowing about if you have sloped or hillside property:

Coastal and inland erosion risk increases when storm-driven rainfall arrives in short, intense bursts rather than spread evenly across the season. It's not just about how much rain falls, it's about how fast it falls and how saturated the ground already is when the next storm hits.

Slopes that were already borderline, areas with bare patches, past erosion, or no stabilization work, carry less margin for error this year than in an average winter. UC San Diego climate researcher Alexander Gershunov has noted a higher likelihood of coastal erosion events during El Nino winters specifically because storm activity in the northeastern Pacific tends to intensify.

Burn-scarred and recently disturbed slopes face elevated debris flow risk. UC Agriculture and Natural Resources is actively running erosion mitigation workshops in the Altadena burn zone right now, since fire-damaged soil sheds water differently and holds together less well under sustained rain. Their guidance: cap exposed soil with compost before the rain starts, not after.

None of this is meant to be alarming for its own sake. It's meant to be useful. A slope that's properly stabilized before the ground saturates behaves completely differently than one that isn't, regardless of how strong the storm season turns out to be.





Why September and October Are the Window That Matters

Search interest in erosion control rises every year in September and October, before a single major storm has hit. That's not a coincidence. People start looking for solutions while the ground is still dry and their options are still open.

This year that window has a hard deadline attached to it. Los Angeles County Public Works is targeting October 15 to have its debris basins cleared and ready, the date it considers the traditional start of rainy season. That's the same logic that applies to your own property: once the rain starts, three things change at once. The ground is too saturated for many installation methods, contractors and installers get booked solid, and any existing erosion issues get worse instead of staying static.

Landscape architect Esther Margulies, who directs USC's graduate programs in landscape architecture and urbanism, put it simply: the key is to start preparing before storms begin, not once they've arrived. That means testing your drains now, not in November.

Check out this recently completed project on a lakeside in Alabama by Moss Landscape Design Group

The same slope form above after- previous project in Georgia, completed by Moss Landscaping Design Group

Your Pre-Winter Slope Checklist

A few things worth walking your property and checking before the rain starts:

Look for bare or washed-out patches. Exposed soil with no root structure or ground cover is the first place erosion accelerates once heavy rain starts.

Check where water pools after a normal rain. Areas that collect water near your foundation, fence line, or at the base of a slope often point to a drainage or grading issue that gets significantly worse under sustained storm conditions.

Inspect any existing retaining walls for cracks, bowing, or leaning, and clear the weep holes. On hillside properties, the biggest threat usually isn't the rain itself, it's the weight of saturated soil pushing against a retaining wall with blocked drainage. Clogged weep holes turn a stable wall into a liability fast.

Clear gutters, downspouts, and drainage inlets near the slope, and make sure downspouts discharge well away from the base of the slope rather than directly onto it. A single blocked downspout can send a significant volume of water onto already-saturated soil during a heavy storm.

Get an actual estimate on your slope, not a guess. The only way to know whether your hillside needs stabilization work, and how urgent that work is, is to have it evaluated directly.

What Actually Stops a Slope From Failing

Surface fixes like mulch, straw wattles, and erosion blankets can help temporarily on mild slopes, but they're not built to hold through a full, intense storm season on a slope that's already unstable. For slopes with real grade, erosion-control professionals and geotechnical engineers point to structural stabilization and terracing as the more durable long-term solution, especially for hillside properties where a soils report would typically be recommended before any major work.

This is exactly where Dirt Locker fits. Our system uses interlocking, 100% recycled HDPE units, made from the equivalent of 13 recycled milk jugs per unit, to physically stabilize a slope from the inside, not just cover it. No permits, no heavy equipment, and once it's planted in, no constant upkeep. Every completed order also funds the planting of 10 or more trees, so the environmental impact runs in both directions: less plastic in landfills, more trees in the ground.

Slopes stabilized with the Dirt Locker system don't just survive a wet season, they get stronger over time as root systems establish through the structure. That's the difference between a slope that's merely covered and one that's actually held.

The Bottom Line

A historic El Nino doesn't have to mean a damaged hillside. It means the slopes that get attention now, while the ground is still dry and contractors still have availability, go into winter with a real plan instead of a hope.

If your hillside has been on your list for a while, this is the window to move on it. 
Use the free project estimator to find out exactly what your slope needs, or send us an email to understand what your slope needs before the storm arrives. 

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FAQ 

Is this El Nino really going to be historic? NOAA's Climate Prediction Center's latest update (September 10, 2026) puts the odds of a very strong El Nino at greater than 90 percent for fall and winter 2026-27, with a 75 percent chance the event exceeds every El Nino on record since 1950. California took this seriously enough that Governor Newsom declared a state of emergency on September 21 to get ahead of it. Forecasts describe probabilities, not guarantees, but the confidence level here is unusually high.

How do I know if my slope is at risk? Look for bare or washed-out patches, water pooling near the base of the slope or your foundation, cracks or leaning in any existing retaining walls, and clogged weep holes. If your property sits in or near a wildfire burn scar, the risk is elevated further since burned soil holds together less well under heavy rain. If you're not sure, a professional estimate is the fastest way to get a direct answer.

When should I start preparing my hillside? As early as possible, ideally in September or October, before the ground saturates and before the first major storm arrives. Los Angeles County is targeting October 15 to have its own flood infrastructure ready, which is a reasonable deadline to hold yourself to as well.

Will mulch or erosion blankets be enough? For mild slopes, temporary coverings can help in the short term. For slopes with real grade or a history of erosion, structural stabilization is generally the more durable long-term answer, since surface coverings don't address what's happening underneath the soil.

Does Dirt Locker require permits or heavy equipment to install? No. The system is designed to be installed without permits or heavy machinery, which is part of why it works for both DIY homeowners and professional installers.

What happens to my slope after it's stabilized? The system gets stronger over time as plant roots establish through the structure. Unlike surface fixes that need to be reapplied each season, a properly installed Dirt Locker system is built to hold with minimal ongoing maintenance.

How is Dirt Locker connected to sustainability? Each unit is made from 100% recycled HDPE, the equivalent of 13 recycled milk jugs. Every completed order also funds the planting of 10 or more trees.

How do I get started? Use the free project estimator to find out exactly what your slope needs, or send us an email with your questions!

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RESOURCE LINKS & SOURCES CITED

• NOAA Climate Prediction Center, official ENSO Diagnostic Discussion (primary source, >90% very strong / 75% historic odds): https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml
• Governor of California, official state of emergency proclamation (Sept 21, 2026): https://www.gov.ca.gov/2026/09/21/governor-newsom-proclaims-state-of-emergency-to-bolster-statewide-el-nino-preparedness-protect-california/
• Los Angeles Times, expert-sourced hillside and drainage prep guidance (Esther Margulies, USC): https://www.latimes.com/california/story/2026-09-22/california-braces-for-super-el-nino-heres-how-to-prepare
• ABC News, coastal erosion and sea level risk (Alexander Gershunov, Scripps/UC San Diego): https://www-cdn.abcnews.com/US/stressful-winter-el-nino-fueled-coastal-erosion-california/story?id=136537040
• UC Agriculture and Natural Resources, Altadena burn scar erosion mitigation: https://www.ucanr.edu/blog/green-blog/article/altadena-erosion
• Melissa Menard (Compass), hillside vs. flat property risk breakdown and geotechnical guidance: https://melissamenardhomes.com/blog/preparing-your-los-angeles-home-for-a-super-el-nino-a-masterclass-in-weather-resilient-real-estate/
• NENC-LA, LA County Public Works debris basin readiness timeline (Oct 15 target): https://nenc-la.org/2026/09/california-declares-state-of-emergency-ahead-of-potentially-historic-el-nino/
• Newsweek, NOAA CPC winter outlook quotes (Scott Handel, NOAA lead meteorologist): https://www.newsweek.com/el-nino-rain-map-shows-states-facing-wetter-than-normal-winter-12461424
• US EPA, Comprehensive Procurement Guidelines for Landscaping Products (recycled HDPE materials): https://www.epa.gov/smm/comprehensive-procurement-guidelines-landscaping-products