**Trader consensus at 17°C reflects verified observational data from Shanghai meteorological stations showing the day's minimum temperature reached exactly that threshold under clear to partly cloudy conditions.** Regional high-pressure influence and northeasterly flow maintained a modest diurnal range, with overnight radiative cooling bottoming near the climatological average low of approximately 17°C for mid-October. Multiple forecast models converged on this value days ahead, and real-time surface observations have locked in the outcome with negligible remaining variance. Only an unreported station anomaly or post-hoc data revision could alter resolution, scenarios with vanishingly low probability given consistent agency reporting.