Climate almanac
O'Fallon
Illinois, United States · 38.59°, -89.91°
What is the weather like in O'Fallon in January?
In January, O'Fallon is typically 41°F (5°C) during the day and 27°F (-3°C) at night. The month brings about 3.3 in (83 mm) of precipitation in total. Snowfall averages about 4.2 in (108 mm) over the month.
- Average high41°F (5°C)
- Average low27°F (-3°C)
- Precipitation3.3 in (83 mm)
- Clear or mostly clear days8
- Snowfall4.2 in (108 mm)
- Based on2016-2025 daily ERA5 reanalysis data (10-year normals)