Tokyo's typical late-August nocturnal cooling is limited by the urban heat island, high humidity, and seasonal sea-surface temperatures that keep minimums clustered near 24–26°C. Current forecasts from the Japan Meteorological Agency and ensemble models indicate a low of approximately 25°C for August 20 under partly cloudy skies with possible showers, aligning with the market's leading 49.5% implied probability on 25°C and 24% on 26°C. No major synoptic shifts—such as a passing front or typhoon influence—are expected in the next 24 hours to push temperatures outside this narrow range, while historical climatology shows August lows rarely deviate more than a degree or two from these values absent extreme events.