Shanghai High School typically follows the standard academic calendar for schools in Shanghai, China. The school year usually begins in early September and concludes in late June or early July. Therefore, Shanghai High School is expected to start in early September.

The reason for this timing is rooted in the Chinese educational system's adherence to a structured academic calendar. According to data from the Shanghai Education Commission, the academic year is divided into two semesters, with the first semester starting in September and ending in January, and the second semester commencing in February and concluding in June or July. This schedule allows for a balanced distribution of teaching and examination periods, ensuring students receive comprehensive education throughout the year. Additionally, the start of the school year in September aligns with the beginning of the new fiscal year in China, which is beneficial for administrative and financial planning purposes.