Real-time observations from the Japan Meteorological Agency confirm Tokyo's daily maximum temperature stabilized at 21°C on September 11, 2026, under persistent cloud cover, light northerly winds, and scattered drizzle that suppressed further warming. This aligns with early-autumn climatology for the region, where September highs typically average near 27°C but drop notably with marine influence and frontal activity. Trader consensus at 100% implied probability for exactly 21°C reflects verified station data late in the day, leaving minimal room for revision. Only an unexpected late surge above 22°C or post-analysis adjustment to the official record could shift the outcome, though current model runs and surface reports show no such potential.