Recent JMA and ensemble forecasts for Tokyo on August 25 show model spread centered near 33–35°C, driving the market’s tight clustering around 33°C and 34°C. Southerly flow off the Pacific high is expected to advect warm, humid air, but differences in predicted cloud cover, timing of any diurnal convection, and boundary-layer mixing determine whether peak insolation pushes readings to 35°C or holds them near seasonal norms of 32–33°C. Official guidance notes elevated heat risk with dew points near 25–27°C, while recent days of 31–33°C highs provide limited precedent for sharper day-to-day jumps absent a stronger ridge. Updated model runs and JMA briefings over the next 48 hours will likely resolve the 1–2°C uncertainty reflected in current trader consensus.