This is part of a series of questions on the predictions from the last Global Annual to Decadal Climate Update from the World Meteorological Organization.

In last year’s report there was no clear signal for the El Niño Southern Oscillation and a weak La Niña was observed for the third year in a row. This La Niña is predicted to decline, and the multi-model ensemble-mean temperature anomalies in the Niño 3.4 region are predicted to be positive for December 2023 – February 2024, indicating the onset of El Niño. There is a large ensemble spread (±1 ˚C) and skill is medium for year 1 (Figure 6). The five-year average temperature in the Niño 3.4 region relative to the whole tropics has a 92% calibrated probability of being above average. Skill is medium, giving medium confidence in this forecast.

Will the WMO indeed report a positive mean temperature anomaly across the region during this period? 