Recent forecast model runs highlight persistent cloud cover, widespread rain, and northerly winds associated with a frontal boundary, limiting daytime heating and promoting modest overnight radiative cooling over Tokyo. These conditions anchor the minimum temperature near the historical early-September baseline of roughly 22°C while introducing uncertainty from exact rainfall timing and wind speeds. The closely matched 22–23°C market-implied odds reflect trader consensus on this narrow range, with slight model divergences in boundary-layer moisture and advection of cooler air determining whether the low settles at 22°C or edges to 23°C. Updated guidance expected from the Japan Meteorological Agency in the next 24–48 hours will likely refine these probabilities.