Which department was in charge of weather forecasting in ancient China?

Qin Tianjian

Official signature. Use the palm to observe celestial phenomena and calculate solar terms and calendars. Since the Qin and Han Dynasties, Taishi Ling has also been in charge of the celestial calendar.

Si Tiantai was first established in the Tang Dynasty. In the Song and Yuan Dynasties, it was called Sitianjian and was juxtaposed with Taishi Bureau and Taishiyuan. Yuan set back to Si Tianjian again. In the Ming and Qing Dynasties, the name was changed to Qintianjian, and officials such as chief supervisor and deputy supervisor were established.