About Altamont, IL's Climate & Weather History

With a population of around 2,300, Altamont sits in Illinois, United States. The city operates in the Central Time Zone.

In 2025, Altamont recorded an average annual temperature of 55°F. The hottest temperatures reached 95°F in September; the coolest were -2°F in January. Total precipitation for the year was 38 inches, with the wettest month being April. Snowfall for the year totaled approximately 8 inches.