Overview

• The WMO’s 2 September update estimates a 55% chance of La Niña for September–November and about 60% for October–December.
• ENSO-neutral conditions have persisted since March after a brief, weak La Niña early in 2025, with cooling potentially redeveloping from September.
• The outlook projects above-normal temperatures for September–November across much of the Northern Hemisphere and large parts of the Southern Hemisphere.
• The likelihood of El Niño developing between September and December remains low, according to WMO producing centres.
• WMO notes forecasts are probabilistic and incorporate other climate drivers such as the North Atlantic Oscillation, Arctic Oscillation and Indian Ocean Dipole, supporting planning for agriculture, energy, health and disaster response.