Global Seasonal Climate Update for August-September-October 2026

Key messages:

• A strong El Niño is developing and expected to strengthen during August–October 2026
• Above-normal temperatures are expected worldwide.
• Rainfall patterns show a classic El Niño footprint: Wetter conditions are expected in some regions, while drought risk increases in others
• A positive Indian Ocean Dipole is expected to develop
• Forecasts provide a window for early action and support decision making
• WMO community mobilizes to save lives and livelihoods

Outlook for Oceanic Drivers for the Next Season: For the August–October 2026 (ASO 2026) season, the multi-model ensemble (MME) indicates a rapid development toward strong El Niño conditions. The seasonal average SST anomaly is forecast to reach approximately 2.9°C during ASO 2026, with the intensification trajectory peaking in November. The spread among individual forecast systems remains narrow, reflecting high forecast confidence.

In the Indian Ocean, a positive IOD phase is also expected to develop, reaching an ASO 2026 seasonal mean value of 0.6°C. Meanwhile, the equatorial Atlantic basin is forecast to remain generally warm, with SSTs in both the North and South Tropical Atlantic remaining above normal.