A developing super El Niño event, with Niño 3.4 sea surface temperature anomalies already exceeding +2.5°C and multi-model forecasts projecting peaks near +3–4°C by late 2026, represents the dominant near-term driver elevating September 2026 temperatures. This combines with the long-term anthropogenic warming trend that has placed 2023–2025 as the three warmest years on record across major datasets, keeping baseline conditions elevated. Recent August 2026 global ocean temperatures reached new daily highs, and seasonal outlooks from NOAA and the WMO indicate widespread above-normal land and ocean temperatures through September–November, though El Niño’s full global temperature response typically lags peak Pacific warming by several months. Market-implied odds favoring a second-hottest September reflect expectations that these factors will sustain high anomalies without quite matching the record set under prior strong El Niño influence, while leaving room for first- or third-place outcomes depending on the final monthly anomaly relative to historical baselines from agencies such as Berkeley Earth and Copernicus. Updated seasonal forecasts and September temperature releases will provide the next key data points for traders.