Global Seasonal Climate Update for September-October-November 2026
Outlook for Oceanic Drivers for the Next Season: For the September–November 2026 (SON 2026) season, multi-model ensemble (MME) forecasts indicate a further development toward stronger El Niño conditions. The seasonal average Niño 3.4 SST ensemble mean anomaly is forecast to reach approximately 3.6°C during SON 2026, with the intensification trajectory peaking in November-December. The spread among individual forecast systems generally remains narrow, reflecting high forecast confidence.
In the Indian Ocean, a positive IOD phase is also expected to develop, reaching an SON 2026 seasonal mean value of 0.9°C. Meanwhile, the equatorial Atlantic basin is forecast to remain generally warm, with SSTs in both the North and South Tropical Atlantic staying above normal.
About the Global Seasonal Climate Updates series
The Global Seasonal Climate Update (GSCU) is WMO's flagship seasonal climate outlook, providing authoritative information on the current state of the climate system and expected temperature and rainfall patterns for the coming three months. Issued monthly, the GSCU brings together the latest global climate science to support informed decision-making worldwide.
