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Climate almanac

Mount Vernon

Illinois, United States · 38.32°, -88.90°

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What is the weather like in Mount Vernon in September?

In September, Mount Vernon is typically 83°F (28°C) during the day and 63°F (17°C) at night. The month brings about 3.1 in (78 mm) of precipitation in total.

  • Average high83°F (28°C)
  • Average low63°F (17°C)
  • Precipitation3.1 in (78 mm)
  • Clear or mostly clear days15
  • Based on2016-2025 daily ERA5 reanalysis data (10-year normals)