Japan's weather agency reports record El Niño sea temperature anomaly for September

On 10 October 2026, the Japan Meteorological Agency (JMA), the country's national weather service, reported that the sea-surface temperature deviation off Peru in September was the largest since records began. The figure measured how far ocean temperatures in the eastern Pacific stood above their long-term average.

El Niño is a periodic warming of the tropical Pacific that shifts rainfall and temperature patterns around the world. It is typically linked to heavier rain and flooding along the Peruvian coast, drought in parts of Southeast Asia and Australia, and a boost to global average temperatures. JMA publishes monthly monitoring bulletins around the 10th of each month and declares an El Niño when deviations stay well above normal for an extended period.

The September reading mattered because it marked the event as record-strength, raising concern about fisheries, agriculture and weather extremes in the months ahead. It set the baseline against which the larger October anomaly off Peru, reported later, was compared.