Updated ensemble forecasts from the GFS and ECMWF models indicate overnight lows in Shanghai stabilizing near 19–21°C on May 20, driven by persistent southerly flow, elevated dew points near 18°C, and limited radiative cooling under partly cloudy skies. This aligns with Shanghai’s May climatology, where average minima rise from 16–17°C early in the month to 18–20°C by mid-to-late May under neutral ENSO conditions. Recent surface observations from Pudong International Airport show a warming trend since mid-month, with urban heat-island effects further moderating temperature drops. Trader consensus assigns the highest implied probability to 15°C or below while spreading significant weight across the 19–22°C range, reflecting genuine uncertainty from variable cloud cover and potential frontal passages. New model runs and China Meteorological Administration guidance expected within 48 hours will refine the resolution threshold.