The city receives an average of 46 inches of rainfall annually, with May being the wettest month. The major hydrology constituent in the area is Crab Orchard Lake, a 6,965-acre man-made reservoir located just south of Carterville. It is a popular spot for fishing, boating, and camping. Additionally, the city has a variety of parks, including Cannon Park and Lions Park, which offer hiking and biking trails, playgrounds, and picnic areas. The Williamson County Trail System, a network of multi-use trails, also runs through Carterville, providing opportunities for outdoor recreation.
Carterville receives approximately 1174mm of rain per year, with humidity levels near 84% and air temperatures averaging around 14°C. Carterville has a plant hardyness factor of 6, meaning plants and agriculture in this region thrive during a short period during spring and early summer. Most plants will die off during the colder winter months.