Climate almanac

Decatur

Illinois, United States · 39.84°, -88.95°

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What is the weather like in Decatur in December?

In December, Decatur is typically 43°F (6°C) during the day and 29°F (-2°C) at night. The month brings about 2.3 in (59 mm) of precipitation in total. Snowfall averages about 2.1 in (53 mm) over the month.

  • Average high43°F (6°C)
  • Average low29°F (-2°C)
  • Precipitation2.3 in (59 mm)
  • Clear or mostly clear days7
  • Snowfall2.1 in (53 mm)
  • Based on2016-2025 daily ERA5 reanalysis data (10-year normals)