Recent forecasts from JMA, GFS, and ECMWF runs indicate a transition to overcast skies, widespread rain or thunderstorms, and northerly/northeasterly winds on September 3–4, suppressing daytime heating and limiting nocturnal radiative cooling. This setup favors minimum temperatures clustered near 20–24 °C, with ensemble spreads reflecting modest uncertainty in exact wind speed, cloud thickness, and precipitation timing that can shift the low by 1–2 °C. Historical September climatology for Tokyo places typical overnight minima around 22 °C, so the current pattern represents a modest cool anomaly driven by the synoptic shift rather than a deeper cold-air intrusion. Traders are therefore weighting the 19–24 °C outcomes most heavily while assigning lower probability to extremes outside that range, pending the next official JMA update and higher-resolution model guidance expected within 24 hours.