The bars show the chance of El Niño (red bars), ENSO-Neutral (grey bars), and La Niña (blue bars) provided for 9 upcoming, overlapping 3-month seasons (each letter represents a month, for example, F = February). The color shading within the bars indicates the chances of different categories of El Niño or La Niña strength (weak, moderate, strong, and very strong). Alternatively, the table presents the percent chances of each strength category in numerical form.
The official outlook is determined by a ~10 member team, using available insights from multiple models (multi-model ensembles) and the latest observations using climate reanalysis, in situ measurements, and satellite data.
Probabilities are verified using the Relative Oceanic Niño Index (RONI), using incremental -/+ 0.5 degree Celsius thresholds in sea surface temperature departures averaged in the Niño-3.4 region of the east-central equatorial Pacific Ocean (170–120W, 5S–5N). The 1991–2020 climatological base period is used to define the departures.
The strength of El Niño or La Niña does not necessarily correspond with the strength of the influence or expected impact. Stronger El Niño or La Niña events often tend to be accompanied by higher certainty in the expected El Niño or La Niña impact, but never guarantees them (e.g. higher chances of above-average precipitation in a certain region of the country). Please refer to CPC's official seasonal outlook for chances of temperature and precipitation for upcoming seasons.
A 0% chance is approximate and not exact, meaning there is still some finite, non-zero chance (e.g. .01%) of the outcome occurring.
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