Weekly update · December 17, 2025
El Niño Update, Week of December 17, 2025: Niño 3.4 at -0.7 °C
In the week of December 17, 2025, the sea surface temperature anomaly in the Niño 3.4 region — NOAA's main El Niño indicator — was -0.7 °C (25.9 °C actual), which corresponds to La Niña conditions.
Compared with the previous week it held steady, and over the last four weeks it rose 0.1 °C.
Off the coast of Peru and Ecuador (Niño 1+2) the anomaly was -0.5 °C (it fell 0.2 °C); this coastal warming is what most affects rain on the South American Pacific coast.
One year earlier, Niño 3.4 was at -0.8 °C.
| Region | Area | Anomaly | vs. last week |
|---|---|---|---|
| Niño 1+2 | coast of Peru and Ecuador | -0.5 °C | -0.20 |
| Niño 3 | eastern Pacific | -0.9 °C | -0.10 |
| Niño 3.4 | central Pacific (official index) | -0.7 °C | 0.00 |
| Niño 4 | western-central Pacific | -0.3 °C | 0.00 |
Niño 3.4, previous 52 weeks
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Frequently asked questions
Was there an El Niño in the week of December 17, 2025?
The weekly Niño 3.4 anomaly was -0.7 °C, below the −0.5 °C La Niña threshold. NOAA declares an event using the 3-month ONI and the atmospheric response.
Where do these numbers come from?
From NOAA's Climate Prediction Center weekly OISST v2.1 sea surface temperature data, published every Monday.
Source: NOAA CPC weekly OISST v2.1 (public domain). Generated automatically by El Niño Forecast; free to cite with a link.