**Traders have converged on 21°C as the near-certain outcome for Shanghai’s lowest temperature on June 11, 2026, reflecting short-range forecast consensus from the China Meteorological Administration and international models.** Typical early-June conditions in the Yangtze Delta—high humidity, frequent cloud cover, and light winds under the East Asian monsoon—limit nighttime radiative cooling and keep overnight lows near 20–22°C. Recent observations show daytime highs reaching 32–34°C with minimal diurnal range, consistent with climatological averages of 21–23°C for mid-June minima. The market-implied 100% probability on 21°C indicates skin-in-the-game alignment around the official forecast threshold, where even small revisions could shift resolution. A realistic challenge would require unexpected clear skies or a model update pushing the minimum outside the 21°C bracket by measurement time at the primary Shanghai station.