Official forecasts from the Japan Meteorological Agency peg Tokyo’s September 5 high at 25°C under persistent cloud cover, scattered showers, and northeasterly flow that suppresses daytime heating. Multiple numerical models align on this value, reflecting typical early-September climatology of 26–29°C highs tempered by the current synoptic pattern. Trader consensus at 100% implied probability for exactly 25°C rests on this model agreement and the expectation that final station readings will fall within rounding thresholds used for market resolution. Only a sharp, unexpected clearing trend or localized urban heat-island spike could push the verified maximum outside the 25°C bin.