**Forecast consensus from global and regional models positions 23°C as the clear leader for Tokyo’s October 4 high, aligning with the market’s 58% implied probability.** Recent runs show a stable autumn pattern with northerly flow and extensive cloud cover suppressing daytime heating after a 23.9°C peak on October 3. Ensemble guidance clusters tightly between 22–24°C, with minimal spread due to absent frontal systems or tropical moisture. Traders have concentrated risk on these central outcomes because historical October variability in the Kanto region rarely produces outliers once mid-level ridging sets in. Updated Japan Meteorological Agency and GFS runs tomorrow morning represent the last major data point before official observations resolve the market.