Persistent rain and extensive cloud cover from subtropical moisture are the main drivers keeping Taipei's overnight minimum near 25°C, as reduced radiative cooling and high humidity (often above 90%) limit temperature drops despite light winds. Official forecasts from sources like the Central Weather Administration and global models consistently project lows of 24–26°C under these conditions, with heavy showers through the evening further moderating cooling rates compared to clearer historical September nights averaging around 23°C. Close market odds between 25°C and 22°C reflect uncertainty in exact rain timing and localized urban heat effects, while lower probabilities for 21°C or below align with the low likelihood of significant clearing before dawn. Updated model runs and real-time observations will refine these near-term thresholds.