Forecast uncertainty for Jinan’s minimum temperature on September 21 stems from variable cloud cover and light northeasterly winds that will influence overnight radiative cooling. Multiple models indicate a most likely low near 20–22 °C, consistent with recent observations of 21–24 °C under partly cloudy skies and 19 % drizzle risk. However, clearer breaks could allow stronger cooling toward the mid-teens, while lingering moisture or reduced wind might hold readings above 22 °C. This genuine spread in guidance, typical for transitional autumn nights when high pressure begins to build, explains the near-even market split between sub-12 °C and 22 °C-plus outcomes. Traders will watch the next China Meteorological Administration update and evening model runs for resolution signals.