Station: Alton, MO. U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). National Oceanic and Atmospheric Administration. [2021-08-03]. (原始内容存档于2023-04-27).
Station: Alton, MO. U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). National Oceanic and Atmospheric Administration. [2021-08-03]. (原始内容存档于2023-04-27).