Short-term ensemble forecasts from major models like ECMWF and GFS are anchoring trader sentiment around 23–24°C for Shanghai’s official minimum on June 21, reflecting typical early-summer conditions during the East Asian monsoon transition. Persistent cloud cover and high humidity limit nighttime radiative cooling, while urban heat-island effects from the metropolitan area tend to hold minimums near or slightly above the long-term June climatology of 20–22°C. Light steering winds and any lingering moisture from plum-rain patterns further stabilize temperatures in this narrow band. With the leading outcomes tightly matched at 33–35% implied probability, the market highlights genuine forecast uncertainty that upcoming 48-hour model runs and official station observations will likely resolve.