| Date | Event and so what | Source(s) |
| January | Last January, satellite radar detected a swell of warm water surging through Oceania, in the western Pacific, at about two meters per second. (Degroot, 2026, Sept 2) | |
| March | In March, instruments picked up another, similar pulse of warm water as it pushed east across the Pacific Observations of these Kelvin waves sparked widespread concern, because they seemed like sure signs of a pending El Niño. And indeed, computer models of Earth’s climate began to forecast not just any El Niño, but a monster event that seemed poised to dramatically amplify global warming. (Degroot, 2026, Sept 2) March 6 – International Sea Level Satellite Observes El Niño Precursor https://science.nasa.gov/photojournal/international-sea-level-satellite-observes-el-nino-precursor/ | |
| June | Midway through June, the National Oceanic and Atmospheric Administration (NOAA) announced that El Niño had officially begun. (Degroot, 2026, Sept 2)June 11 – El Nino forms, expected to strengthen, say NOAA forecasters | |
| September | WMO press release | |
| September | Climate Impacts Labs gets the first well-circulated number for deaths out – 450k (often rounded up to ‘half a million’ | |