Climate almanac

Decatur

Illinois, United States · 39.84°, -88.95°

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What is the weather like in Decatur in January?

In January, Decatur is typically 37°F (3°C) during the day and 23°F (-5°C) at night. The month brings about 2.8 in (72 mm) of precipitation in total. Snowfall averages about 4.8 in (123 mm) over the month.

  • Average high37°F (3°C)
  • Average low23°F (-5°C)
  • Precipitation2.8 in (72 mm)
  • Clear or mostly clear days7
  • Snowfall4.8 in (123 mm)
  • Based on2016-2025 daily ERA5 reanalysis data (10-year normals)