Recent meteorological observations and ensemble model guidance for Jinan indicate minimum temperatures clustering near 17–19 °C, sustaining tight market-implied odds across these outcomes. Diurnal radiative cooling under clear to partly cloudy skies, combined with light northerly flow from the East Asian monsoon transition, limits further nocturnal temperature drops while urban heat-island effects in Shandong’s capital moderate the low. Historical September climatology shows average overnight minima around 18 °C, with interannual variability driven by the position of the subtropical high and any incoming cold-air intrusions. Traders weigh these factors against the day’s remaining observational window, as additional surface data or revised short-range forecasts could shift the recorded low before resolution.