The National Oceanic and Atmospheric Administration (NOAA) has raised the chance of a historic event exceeding every El Niño since 1950 to 83 percent, up from 75 percent in September and 69 percent in August. It now puts a very strong event at 100 percent through October to December. The World Meteorological Organization (WMO) consensus expects the event to peak around December and persist through February 2027. September 2026 was 1.63°C above pre-industrial, the second-warmest September on record, with the highest September sea surface temperature ever measured.

Impacts will outlast the ocean peak by more than a year. The failed rainy season in Sudan, South Sudan, northern Ethiopia and Eritrea now overlaps with flood risk in the southern Greater Horn. The Famine Early Warning Systems Network (FEWS NET) places the peak of southern African food needs in the November 2027 to March 2028 lean season. This bulletin supersedes Science Bulletin No. 6.