A weak cold front approaching Beijing on May 17 is moderating daytime heating through northerly winds, light rain, and widespread cloud cover that reduces solar insolation and keeps surface temperatures in check. Official guidance from the China Meteorological Administration, along with ECMWF and GFS model ensembles, currently clusters the daily maximum near 20°C, with slight variations depending on the exact timing of frontal passage and any breaks in overcast conditions. Earlier clearing could allow brief warming to 22–23°C, while sustained cloudiness and boundary-layer mixing from wind shear favor readings closer to 18–19°C. Traders have priced this narrow range tightly because short-term model updates and morning observations will resolve lingering uncertainty before the market settles.