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Climate almanac

Washington

Illinois, United States · 40.70°, -89.41°

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What is the weather like in Washington in September?

In September, Washington is typically 80°F (27°C) during the day and 60°F (15°C) at night. The month brings about 2.5 in (63 mm) of precipitation in total.

  • Average high80°F (27°C)
  • Average low60°F (15°C)
  • Precipitation2.5 in (63 mm)
  • Clear or mostly clear days15
  • Based on2016-2025 daily ERA5 reanalysis data (10-year normals)