Recent ensemble forecasts from the Japan Meteorological Agency and global models show Tokyo’s minimum temperature on May 24 centered near 14–15 °C, with modest spread arising from uncertainty in nocturnal cloud cover and weak southerly flow. Clear skies under a building subtropical high would allow greater radiative cooling and favor the lower outcomes now leading the market, while increased low-level moisture or a passing short-wave trough could limit the overnight drop and support the 17–18 °C cluster. Historical May climatology places average lows near 15 °C, so current model consensus aligns closely with that baseline while highlighting the narrow window for meaningful forecast shifts before the 24th.