About Altamont, IL

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

Recent weather here gives a sense of typical conditions: in 2025, Altamont recorded a mean annual temperature of 55°F, ranging from -2°F lows in January to 95°F highs in September, with about 38 inches of precipitation across the year.