A Pacific signal without precedent
The World Meteorological Organization expects the current El Nino to strengthen into the strongest event since observations began. In its Global Seasonal Climate Update, the agency projects a seasonal average sea surface temperature anomaly of about +3.8C in the Nino 3.4 region for November 2026 to January 2027, with warming peaking around December. The previous record was +2.6C in the 2015-16 event.
WMO puts the likelihood that El Nino persists through February 2027 at close to 100%. Its secretary-general, Celeste Saulo, said the event is firmly established and strengthening rapidly, and could rank among the strongest since at least 1950.
Heat, drought and flood in the same season
The outlook points to above-average temperatures over almost all land areas in the coming months, with rainfall patterns shifting in a classic response to a strong Pacific El Nino. That combination raises drought risk in some regions and flood risk in others, often within the same country.
Researchers at the University of Chicago's Climate Impact Lab estimate that heat linked to this El Nino could cause about 451,000 additional deaths worldwide between June 2026 and February 2027, with Nigeria facing the largest national toll at roughly 31,400 between September and February. Those projections are modelled estimates, not counts of observed deaths.
The longer trend behind the spike
The forecast lands weeks after UNEP published its Emissions Gap Report 2026, titled The Point of Return. The report concludes that limiting warming to 1.5C without any overshoot is no longer feasible, because of the greenhouse gases already in the atmosphere. It sets out what deep cuts would still achieve: an 18% reduction by 2030, 45% by 2035 and 69% by 2040, measured against a 2025 baseline, or about 5.7% a year.
Under that lowest-overshoot pathway, warming peaks at roughly 1.7C to 1.8C around mid-century, with about an even chance of falling back to 1.5C by 2100. Returning to that level would require removing and permanently storing around 320 gigatonnes of carbon dioxide this century, a scale UNEP describes as uncertain.
UN Secretary-General Antonio Guterres said overshoot is not surrender, and that it can still be kept as small and as short as possible. The report will feed into COP31 negotiations, where countries are due to revise their national pledges.