What every strong El Niño did to every state.
El Niño shifts the odds. It does not guarantee an outcome. So this atlas does not draw one averaged composite. It counts, state by state, how many of the strong El Niño winters since 1950 fell in the warm or cold third (or wet or dry third) of winters, shows every one of those winters, and says when a lean is stronger than chance can explain.
Every state as a table
How to read it, and how far to trust it
The count
For each state and window, winters 1950–51 to 2025–26 are detrended with a straight-line fit, so a recent winter is not called warm just because the climate is warmer. The detrended 1991–2020 winters are split into thirds. Each strong El Niño winter then lands in one third. By chance alone, about 3 of 9 would land in any one of them.
Strong El Niño winters are the ones Golden Gate Weather Services classes as strong or very strong on NOAA's ONI: . Two winters sit right on the 1.5 °C line in today's ONI (1987–88 at 1.49, 2009–10 at 1.50), so every state also shows its count with the two swapped.
The honesty checks
- 95% Wilson interval on every count: with 9 winters, "7 of 9" means somewhere between about 45% and 94%.
- False-discovery control. Across 48 states, a few will lean hard by luck. A state is stippled only if its lean survives Benjamini–Hochberg at q = 0.10 across the whole map.
- 2026–27 odds, history layer. Each strong winter's detrended value is placed on the 2026 trend level and compared with the plain 1991–2020 thirds, beside the same calculation for all 76 winters (the trend alone). That splits the shift into the part warming explains and the part El Niño adds. The model layer, SEAS5 and the Copernicus systems calibrated on their reforecasts, follows on Nov 5.