California is no stranger to El Niño.
The naturally occurring climate pattern can influence rainfall, temperatures, ocean conditions, storms, and coastal hazards across the state. But this year, scientists are watching a particularly powerful El Niño develop in the Pacific—and new research suggests that a warming planet may be making these events stronger.
For California, that makes El Niño more than a weather story.
It is also an environmental health, infrastructure, water-management, and community preparedness issue.
What Is El Niño?
El Niño is a naturally occurring ocean-atmosphere phenomenon associated with unusually warm ocean surface temperatures in the central and eastern tropical Pacific.
Those changes can influence weather patterns far beyond the Pacific.
In California, El Niño has historically been associated with changes in precipitation, storms, coastal conditions, and temperature patterns. However, El Niño does not guarantee a particular outcome for every location or season.
What makes the current situation especially important is its projected strength.
According to NOAA's Climate Prediction Center, El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter of 2026–27. NOAA also estimates a 69% chance that the October–December period could produce an event reaching historic strength compared with El Niño events dating back to 1950.
Why Climate Change Matters
El Niño is not caused by climate change.
It is part of Earth's natural climate variability.
However, scientists are increasingly examining how a warmer planet can change the behavior and consequences of El Niño events.
A new study highlighted by CBS News used long-term coral records to examine historical El Niño conditions. The research adds to evidence that strong El Niño events have become more intense as the planet has warmed.
This distinction is important.
Natural climate variability and human-caused climate change can interact.
A naturally occurring El Niño developing on top of an already warmer climate system can create different conditions than the same climate pattern would have produced decades ago.
California's Ocean Is Already Sending Signals
California's coastal waters are an important part of the story.
Scientists are currently observing unusually warm ocean conditions along the West Coast. CBS News reported that the waters off Southern California and the west coast of Mexico are at record warmth, with climate scientists noting that several factors are contributing—including an existing marine heatwave, the developing El Niño, and long-term human-caused warming.
NOAA Fisheries is also monitoring the West Coast for indicators of El Niño's arrival, including changes in ocean conditions, sea levels, and marine species. The agency notes that some of the unusual warmth currently observed off Southern and Central California predates the current El Niño and is associated with a marine heatwave.
That distinction matters because environmental conditions are rarely caused by a single factor.
What Could This Mean for California?
The strongest effects of this El Niño are expected to become more apparent later in the year.
California climate scientist Daniel Swain told CBS News that the primary California weather impacts of this El Niño could increase in late November and December and potentially continue through March 2027.
Potential concerns include:
Heavy Rain and Flooding
Strong El Niño events can increase the potential for significant precipitation in parts of California.
Heavy rainfall can overwhelm drainage systems, cause flooding, damage infrastructure, trigger landslides, and transport pollutants into waterways.
For communities, preparedness can make a major difference.
Coastal Hazards and Erosion
El Niño can also influence coastal conditions.
Warmer ocean temperatures, elevated sea levels, large waves, and powerful storms can increase stress on beaches, coastal infrastructure, and vulnerable communities.
NOAA Fisheries is specifically monitoring coastally trapped waves and other ocean indicators that can accompany El Niño conditions along the West Coast.
Water Quality
Heavy rainfall doesn't simply disappear after a storm.
Runoff can carry bacteria, sediment, chemicals, trash, nutrients, and other pollutants into rivers, streams, storm drains, and coastal waters.
That means extreme rainfall can become a water-quality issue as well as a flooding issue.
Communities should be prepared to monitor water quality after major storm events, particularly in areas affected by urban runoff, agricultural activity, wastewater infrastructure, or previous contamination.
Marine Ecosystems
The ocean is particularly sensitive to temperature changes.
Warmer waters can place stress on marine organisms and alter the availability of nutrients and oxygen.
CBS News reported that scientists are already concerned about impacts on corals, fish, and other marine organisms as ocean temperatures reach exceptional levels.
NOAA Fisheries is monitoring changes in marine species and ocean indicators as El Niño develops along the West Coast.
Why Environmental Health Professionals Should Pay Attention
Environmental health is about more than responding to contamination after it happens.
It is also about understanding how changing environmental conditions can create new or amplified risks.
A strong El Niño combined with a warmer baseline climate can affect multiple systems at once:
Weather → Water → Infrastructure → Ecosystems → Communities → Public Health
That interconnectedness is why preparation matters.
A flood can damage a wastewater system.
A damaged wastewater system can create contamination.
Contaminated runoff can affect recreational waters.
Poor water quality can create exposure risks for people and wildlife.
One environmental event can therefore trigger a chain of consequences.
Preparing Before the Storm
Residents and businesses do not need to wait for the first major storm to prepare.
Simple steps can reduce potential impacts:
- Clear gutters and storm drains.
- Inspect roofs and drainage systems.
- Secure outdoor equipment and loose materials.
- Check emergency lighting and batteries.
- Review emergency communication plans.
- Keep basic emergency supplies available.
- Monitor local weather and flood advisories.
- Know whether your property is located in a flood-prone area.
- Be cautious around flooded roads and contaminated floodwater.
- Follow local water-quality and beach advisories after major storms.
CBS News similarly recommends checking gutters and downspouts, inspecting roofs, securing yards, and keeping emergency supplies available. Residents in flood-prone locations may also want to prepare sandbags and other basic flood-protection materials.
Preparedness Is an Environmental Health Strategy
Climate-related preparedness is sometimes viewed primarily as an emergency-management responsibility.
But environmental health professionals have an important role as well.
Monitoring environmental conditions, identifying exposure pathways, communicating risks, protecting water quality, and helping communities understand changing hazards are all part of prevention.
The goal is not to predict exactly what every storm will bring.
The goal is to make communities more resilient when conditions change.
The Bigger Picture
The developing 2026–27 El Niño is a reminder that California's environmental challenges are interconnected.
Climate change does not eliminate natural climate patterns like El Niño.
Instead, a warmer planet can change the background conditions in which those natural patterns occur.
That means California must prepare for both natural variability and long-term climate change.
The most effective response is not simply reacting when extreme weather arrives.
It is investing in:
Preparedness.
Monitoring.
Infrastructure resilience.
Water-quality protection.
Environmental stewardship.
Public education.
As California heads toward another potentially significant winter weather season, understanding these connections can help communities prepare before environmental hazards become public health emergencies.
The DSG Perspective
At Definitive Safety Group, we believe prevention is one of the most important tools for protecting people, communities, and the environment.
A changing climate requires more than awareness. It requires preparation, monitoring, and informed decision-making.
Because environmental health doesn't begin after a disaster—it begins with preparation before one.
