**Persistent cloud cover, scattered showers, and moderate humidity from an approaching frontal system are keeping overnight lows in Tokyo elevated around 24–26°C for August 28, aligning with the market’s heaviest trading on 25°C (44.5%) and 26°C (32%).** Japan Meteorological Agency guidance and ensemble forecasts show a minimum near 24°C under mostly cloudy skies with light northeasterly winds and intermittent rain, limiting radiative cooling compared with clearer recent nights. This pattern follows hotter, sunnier conditions on August 26 (highs near 33–35°C) and increasing instability on the 27th. Late-August climatology for Tokyo favors nighttime lows near 22–23°C, but the current moist, overcast regime adds 1–3°C through reduced heat loss and urban heat retention. No strong typhoon or major cold-air advection is expected to alter the setup before resolution. Updated JMA model runs and short-range guidance over the next 24–48 hours remain the key near-term drivers for any shifts in these implied probabilities.