Beijing Weather in October. CityWeather. October in Beijing is very cool and dry, with big temperature differences between day and night. It still feels like summer in the afternoon during a sunny day, but may cool down to 3-4 C (37-39 F) quickly after a few days’ rain. Corresponding to the Descent of Frost, one of the 24 seasonal segments, frost may appear at the end of this month. October is the transitional period from autumn to winter.