What was the occupation of watching the weather in ancient times?

Different dynasties are also different.

Observe astronomical phenomena, calculate solar terms and make calendars. From the Qin and Han Dynasties to the Southern Dynasties, the Emperor Tai Shang belonged to the Taishiling Star Calendar. Sui secretary provincial Taishi Cao, Yang-ti changed Cao to supervisor. At the beginning of the Tang Dynasty, Taishi supervisor was changed to Taishi Bureau, and the successor was renamed Secretary Pavilion, Mixed Day Supervisor, Mixed Justice Supervisor, or Secretary Province several times. In the 14th year of Kaiyuan (726), it was re-established as Taishi Bureau and was the secretary province. In the first year of Gan Yuan (758), it was renamed Si Tiantai. In the Five Dynasties and the Early Song Dynasty, it was called Division, and Yuanfeng was changed to Taishi Bureau after restructuring. The official in southern Liaoning has a supervisor of the Ministry of Heaven, and the gold is called the Tiantai of the Ministry, which belongs to the supervisor of the Department. In the Yuan Dynasty, there was imperial academy, which was juxtaposed with Si Tianjian and Hui Sijian.