Recent ensemble forecasts from the China Meteorological Administration, ECMWF, and GFS models converge on a Beijing high near 20°C for May 17, shaped by a weak cold front ushering northerly flow, light rain, and persistent cloud cover that curbs daytime solar heating. This setup explains the tight clustering of market-implied odds around 19–21°C, with sustained overcast favoring the lower end of that range and any earlier frontal passage or partial clearing allowing brief warming toward 22°C. Mid-May climatology in Beijing typically features highs in the low-to-mid 20s Celsius, but the current frontal influence introduces genuine short-term uncertainty resolvable only by final observational data from official stations.