Governor Newsom proclaimed a statewide emergency on 21 September with no storm in progress. It stages sandbags, pumps, Caltrans equipment and the National Guard, and it unlocks permitting. CPC puts a very strong event above 90%, but CPC also says event strength does not necessarily correspond to impact strength. Both things are true at once.
Governor Newsom proclaimed a statewide emergency on 21 September to prepare California for El Niño. No statewide storm or flood emergency was under way. The proclamation was anticipatory, although recent high surf and coastal flooding had already offered a preview of the coastal risk.
A lot of coverage will read that proclamation as a forecast. It is not one. It is a procurement and logistics instrument, and the distinction is worth ten minutes of anyone's time.
A California emergency proclamation is primarily a legal unlock. It lets the state move faster than normal rules allow, and the operative directions are about staging, not predicting:
Read that list again. Every item is something you do before you know what the winter will do. A sandbag staged in October is not a prediction that it will be filled. It is an admission that if it is needed in January, October was the last cheap moment to move it.
None of which is to be casual about the ocean. The numbers behind this are genuinely at the edge of the record.
CPC's Diagnostic Discussion of 10 September puts a greater than 90% chance of a very strong event across autumn and winter, and a 75% chance that the October to December season exceeds every El Niño back to 1950, defined as a three-month RONI of +2.5°C or more. No event in the 1950 to 2026 record has reached that. The highest is 1982-83 at +2.40.
The observations are keeping pace. Seasonal RONI reached +1.36°C in June to August. In CPC's weekly update published on 21 September, for the week centred 16 September, the relative Niño 3.4 anomaly stood at +2.1°C, with Niño 1+2 at +3.9°C, Niño 3 at +3.0°C and Niño 4 at 0.0°C. Those are relative-index values; the conventional equivalents run roughly 0.8 to 0.9°C higher. That east-weighted structure is the shape of the 1982-83 and 1997-98 events rather than 2015-16, a distinction we have gone into elsewhere.
So California is not overreacting to a marginal signal. It is responding to one of the strongest Pacific configurations ever measured.
Here is the sentence that should govern every story written about this proclamation, and it comes from CPC itself:
"The strength of El Niño or La Niña does not necessarily correspond with the strength of the influence or expected impact."
That is not hedging. It is the actual state of the science. The index measures the tropical Pacific. California's winter is decided by where the North Pacific jet sets up, how often atmospheric rivers make landfall and at what latitude, and how the ridge over the eastern Pacific behaves. El Niño tilts those odds. It does not set them.
The demonstration is 2015-16. On the conventional index it was the strongest event since 1950, stronger by that measure than 1997-98. It was widely expected to end the California drought. Southern California was the conspicuous failure: much of the north received closer-to-normal precipitation, while Southern California remained dry and the statewide drought relief fell well short of expectations. We laid that case out in the California winter outlook, along with why three or four analog events is not a sample you can compute a probability from.
1982-83 and 1997-98 were genuinely wet in California. 2015-16, comparably powerful, was not, and the shortfall was concentrated in the south rather than spread evenly. Two out of three is a tendency. It is not a forecast, and it is certainly not a guarantee.
The more useful point is that the statewide seasonal total is close to the wrong metric anyway.
California damage is not a function of how many inches fall between October and March. It is a function of how they arrive. A season that lands near normal in total but delivers three atmospheric rivers in eleven days onto already saturated ground will do far more harm than a wetter season spread evenly. The specific hazards are all sequence-dependent:
Staged pumps, pre-positioned Caltrans equipment and a Guard ready for search and rescue are all responses to that sequencing risk. They pay off in a near-normal winter that happens to deliver one bad fortnight. It is a scenario worth preparing for even if the statewide seasonal total ultimately finishes near normal, and it is the one the proclamation is actually built for.
The honest position at the end of September is that the Pacific signal is close to a record and the California outcome is not yet determined. These are the things that will decide it, and none of them is an ENSO index.
Confirms the wet expectation: a persistent Aleutian low with an extended, energised subtropical jet aimed at California, and repeated atmospheric-river landfalls south of about 38°N through January to March, which is when California's El Niño precipitation signal is generally strongest, with Southern California precipitation running above normal.
Refutes it: a blocking ridge setting up over the eastern North Pacific and deflecting storms into the Pacific Northwest or Alaska, which is broadly what happened in 2015-16 despite a record index. If Southern California remains materially below normal through February, with the subtropical jet and atmospheric-river corridor still displaced north, the canonical response will have failed to establish during most of its primary window.
By when: CPC's monthly and seasonal precipitation outlooks on 15 October and 19 November, the next ENSO Diagnostic Discussion on 8 October, and Southern California precipitation totals through the January to March peak window. December alone is too early to call it.
California is not declaring that a flood will happen. It is declaring that the cost of being unprepared is now greater than the cost of preparing early. Those are different statements, and only one of them is a forecast.