Traders assign near-certainty to a 31°C high in Beijing on September 13 due to real-time observations and model consensus showing peak afternoon temperatures under clear skies, light northerly winds, and low humidity around 20-40%. Official monitoring stations and ensemble forecasts align on this value, consistent with late-summer patterns where September averages reach about 27°C but recent dry, stable conditions have supported warmer peaks. The market-implied odds reflect aggregated trader assessment of these verified data points rather than speculation. A realistic shift would require substantial model revisions, unexpected cloud cover, or an official station reading deviating due to microclimate effects at the primary measurement site.