**Forecast models and real-time observations from multiple meteorological sources converge on a daily maximum of 26°C for Chengdu on September 13, 2026.** Mid-September marks the seasonal transition toward cooler autumn conditions in the Sichuan Basin, following earlier September highs above 30°C; current atmospheric patterns, including light winds and partial cloud cover, limit further warming while preventing significant cooling. Official guidance from agencies tracking surface temperatures supports this precise peak, aligning with the market's near-certain implied probability for 26°C. Scenarios that could realistically alter the outcome include localized measurement variations at the designated station, unforecasted cloud dissipation leading to brief additional warming, or post-observation adjustments in final data.