California Braces for Strong El Niño. Are Buildings Ready for the Rain?

El Niño could bring wetter-than-average winter to California, worsening drainage problems and threatening foundations, retaining walls and slopes. Alpha Structural's Kyle Tourjé says existing conditions can help owners identify where problems may worsen.

LOS ANGELES, Oct. 27, 2026 /PRNewswire/ -- The National Oceanic and Atmospheric Administration's (NOAA) October 15 U.S. Winter Outlook says wetter-than-average conditions are likely across the southern United States, from California to Florida, as a very strong El Niño influences winter 2026-27.

For California property owners and managers, preparation can extend beyond flood response to evaluating drainage, foundations, retaining walls and slopes before repeated storms arrive. "A single storm may saturate the soil briefly, but repeated storms keep it from drying out between events, so the ground stays saturated and loaded for the whole season," said Kyle Tourjé, Executive Vice President of Alpha Structural, a California structural engineering and construction firm specializing in landslide repair, foundation repair and slope stabilization. "Each storm cycle can saturate deeper layers of soil, widening existing cracks and exacerbate movement, so small problems can grow significantly over the course of a single heavy season."

Repeated Rain Can Change Conditions Around a Building

How a property responds to prolonged rain depends on its foundation type, soil conditions, slope, drainage, retaining systems, age and previous repairs. "As soil becomes saturated, the added weight can increase pressure on retaining walls and worsen existing weaknesses," Tourjé said. "Water that reaches beneath a foundation can soften the supporting soil and cause settlement or uneven movement."

Slope issues may take longer to develop. The U.S. Geological Survey notes that deep-seated landslides are often generated by prolonged above-average rainfall, including during El Niño years, and can severely damage buildings and infrastructure.

Repeated storms can also expose drainage problems that may receive little attention during dry periods. "Downspouts discharging against a foundation or onto a slope, clogged slope and trench drains, and runoff from neighboring properties often go uncorrected until saturated soil starts to move," Tourjé said.

Existing Conditions Provide an Early Warning

Tourjé has seen and fixed some of the more serious problems on hillside properties, particularly slopes with little vegetation or areas built on deeper fill soils. "When these areas became heavily saturated, conditions escalated from minor slides to major ground movement, resulting in major damage" Tourjé said. Retaining walls, foundations, and drainage systems were often affected together, underscoring the importance of evaluating the entire site.

Existing cracking, settlement, and retaining-wall movement can help owners recognize later changes. New or widening cracks, sticking doors or windows, sloping floors, leaning or bulging retaining walls, ponding near foundations and new water intrusion can signal that a building or site is responding poorly to prolonged rain.

Tourjé also recommends documenting cracks, walls and slopes with dated photographs before major storms. Owners can mark the ends of existing cracks and record their location and size, so later changes are easier to identify. Previous repair records, permits, and information about drainage conditions can help engineers determine later whether movement is new, continuing, or stable. "Dated photos taken from the same spots before and after storms give engineers a baseline for comparison," Tourjé said.

Early Evaluation Helps Define What Comes Next

Not every storm-related condition requires the same response. Engineers assess when and where movement occurs and whether it changes as the soil dries. Movement that worsens during rain but stabilizes afterward may point to drainage or near-surface soil conditions. Continued movement after rainfall, deep cracks across a slope or visible ground failure may indicate broader slope instability, while uneven settlement around a structure may point to foundation problems.

Those observations help determine the appropriate response. Drainage improvements may be the first step when water management is the primary issue, while foundation, retaining-wall or slope work may be necessary when drainage alone will not stabilize the condition.

With El Niño approaching, Tourjé warns that unresolved property conditions should not be ignored. "Repeated storms turn these conditions into larger problems," he said. "Erosion can worsen, cracks can widen, and wet soil can put more pressure on retaining walls that were already showing signs of weakness." Identifying drainage problems and signs of structural movement before storms arrive can help owners determine when professional evaluation or repairs may be necessary.

About Alpha Structural, Inc.  

When he saw geological challenges trigger catastrophic building collapses, Dave Tourje, founder of Alpha Structural, Inc., immersed himself in construction repairs and mitigation facing the iconic hillside homes and buildings throughout Los Angeles in the 1980s. He recognized a lack of skilled tradesmen and the need for repairs or upgrades to be engineered and constructed successfully. Today, Alpha Structural is Southern California's premier structural repair and engineering firm. With more than 30 years of experience in foundation repair, hillside stabilization, and seismic retrofitting with challenges of earthquakes, wildfires and landslides, Alpha Structural distinguishes itself by being dual-licensed and authorized by the State of California to both engineer and build in-house—an integration that eliminates miscommunication and cost overruns seen when engineering and construction are handled separately. Alpha Structural is trusted by homeowners, municipalities, and commercial partners alike. For more information visit Alpha Structural.

References:

• National Oceanic and Atmospheric Administration. (2026, October 15). El Niño looms large over U.S. Winter Outlook. noaa.gov/news-release/el-nino-looms-large-over-us-winter-outlook NOAA
• National Weather Service, Climate Prediction Center. (2026, October 15). Prognostic discussion for long-lead seasonal outlooks. National Oceanic and Atmospheric Administration. cpc.ncep.noaa.gov/products/predictions/90day/fxus05.html Centro de Previsão Climática
• U.S. Geological Survey. (2015, August 31). Rainfall and landslides in Southern California. usgs.gov/programs/landslide-hazards/science/rainfall-and-landslides-southern-california

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SOURCE Alpha Structural