Climate almanac
Harrisburg
Illinois, United States · 37.74°, -88.54°
What is the weather like in Harrisburg in December?
In December, Harrisburg is typically 49°F (10°C) during the day and 34°F (1°C) at night. The month brings about 3.3 in (85 mm) of precipitation in total. Snowfall averages about 0.9 in (22 mm) over the month.
- Average high49°F (10°C)
- Average low34°F (1°C)
- Precipitation3.3 in (85 mm)
- Clear or mostly clear days8
- Snowfall0.9 in (22 mm)
- Based on2016-2025 daily ERA5 reanalysis data (10-year normals)