California declares statewide emergency as very strong El Niño develops ahead of 2026-27 winter
California Governor Gavin Newsom proclaimed a statewide emergency on September 21, 2026, to accelerate preparations for potential flooding, landslides, coastal hazards, and other winter impacts as a strengthening El Niño develops in the tropical Pacific. NOAA said there is a greater than 90% chance the event will become very strong during Northern Hemisphere autumn and winter 2026–27.
Sea-surface temperature anomalies across the Pacific Ocean on September 22, 2026. Credit: NOAA Coral Reef Watch
California Governor Gavin Newsom proclaimed a statewide emergency on September 21 to accelerate preparations for potential winter storms associated with a strengthening El Niño. The declaration directs state agencies to stage flood-fighting supplies, prepare vulnerable transportation infrastructure, and coordinate emergency-response resources ahead of the 2026–27 winter.
The proclamation streamlines procurement and directs state agencies to begin flood-risk-reduction work ahead of the coming winter.
The Governor’s Office separately reported that California had already experienced coastal flooding earlier in 2026, distinguishing those observed impacts from the winter hazards addressed by the statewide preparedness declaration.
The National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center (CPC) reported a Niño-3.4 sea-surface temperature anomaly of +1.8°C in its September 10 diagnostic discussion, alongside anomalies of +2.5°C in Niño-3 and +3.4°C in Niño-1+2.
Sea-surface temperature anomalies exceeded +3.0°C in the eastern equatorial Pacific, while widespread subsurface anomalies exceeded +10.0°C at depth. Changes in atmospheric circulation and tropical convection accompanied the ocean warming, reflecting the strengthening El Niño.
NOAA’s September 10 outlook assigned a greater than 90% probability of a very strong El Niño during Northern Hemisphere autumn and winter 2026–27.
The agency also forecast a 75% probability that the three-month Relative Oceanic Niño Index (RONI) would reach at least +2.5°C during October–December 2026, exceeding the strength of previous El Niño events in the record dating back to 1950.
In its seasonal outlook issued at 12:30 UTC on September 17, NOAA favored above-normal precipitation over the southern half of California during October–December 2026.
The area of favored above-normal precipitation expands across California during the subsequent winter periods, with probabilities reaching 50–60% near the coast during December 2026–February 2027, January–March 2027, and February–April 2027.
The Governor’s Office identifies heavy rainfall, strong winds, mountain snowfall, flooding, landslides, debris flows, large waves, and coastal flooding among the potential hazards associated with the approaching winter. Flooding and rockslides are among the conditions that can disrupt road access, while very high tides combined with large waves can contribute to coastal flooding.
The California Department of Transportation (Caltrans) will stage traffic-control, road-closure and snow-removal equipment along highways identified as being at risk from winter weather. The preparations are intended to support transportation operations when storms affect vulnerable routes.
The proclamation also prepares the California National Guard to support flood response, search and rescue, engineering and logistics missions when needed. State environmental and natural resources agencies are directed to facilitate local preparations for flooding, landslides and debris flows through accelerated permitting and other administrative measures.
The Governor’s Office of Emergency Services (Cal OES) has been directed to expand accessible, multilingual preparedness communications covering severe weather, flooding, emergency alerts, evacuation readiness and power outages. Cal OES Director Caroline Thomas Jacobs said the agency is coordinating with state and local partners, conducting advance planning, and identifying potential resource needs before anticipated winter impacts.
References:
1 Governor Newsom proclaims state of emergency to bolster statewide El Niño preparedness, protect California | Governor of California – California Governor’s Office – September 21, 2026
2 Climate Prediction Center – Seasonal Outlook – NOAA/CPC – September 17, 2026
3 Climate Prediction Center: ENSO Diagnostic Discussion – NOAA/CPC – September 10, 2026.
Rishav Kothari is Editor-in-Chief of The Watchers, where he runs the newsroom and covers earthquakes, volcanoes, severe weather and space weather.
