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Illiopolis village, Illinois

Official LSAD Designation: Illiopolis village • Census GEOID: 1737127 • Sangamon County

Climate Normals & Weather Observations

30-year climate normals (1991–2020) and weather observations for Illiopolis village.

Reference Weather Station: DECATUR WTP, IL US (ID: USC00112193) • Located 16.1 miles from community center • Elevation: 194.8 m
Month Average High (°F) Average Low (°F) Mean Temp (°F) Precipitation (in)
January 34.0° 19.7° 26.9° 2.40"
February 39.1° 23.5° 31.3° 2.00"
March 50.8° 32.8° 41.8° 2.64"
April 63.4° 43.3° 53.3° 4.12"
May 73.5° 53.8° 63.7° 4.95"
June 82.2° 63.1° 72.6° 4.73"
July 84.7° 66.5° 75.6° 4.00"
August 83.5° 64.9° 74.2° 3.50"
September 77.7° 57.0° 67.3° 3.08"
October 65.3° 45.7° 55.5° 3.41"
November 50.3° 34.3° 42.3° 3.21"
December 38.6° 25.0° 31.8° 2.40"

Annual Temperature History

2010–2025, completed calendar years only.

NOAA station DECATUR WTP, IL US (ID: USC00112193) • 16.1 miles from community center .

This is the same reference station used for monthly normals.

Annual mean Annual mean of daily highs Annual mean of daily lows
Annual temperature history at DECATUR WTP, IL US Year is the horizontal axis. Annual mean temperature in degrees Fahrenheit is the vertical axis. Dots show recorded years; lines connect consecutive available years only. Missing years are gaps, with no interpolation. Optional dashed lines show annual mean of daily highs and lows. Exact values appear in the data table below. 38.0 45.8 53.5 61.3 69.0 2010 2014 2018 2021 2025 Year Annual mean temperature (°F) 2010: Annual mean 53.1°F 2011: Annual mean 53.7°F 2012: Annual mean 56.1°F 2013: Annual mean 51.5°F 2014: Annual mean 49.4°F 2015: Annual mean 53.2°F 2017: Annual mean 54.9°F 2018: Annual mean 53.0°F 2019: Annual mean 52.6°F 2020: Annual mean 53.7°F 2021: Annual mean 54.0°F 2022: Annual mean 52.7°F 2024: Annual mean 55.2°F 2010: Annual mean of daily highs 62.1°F 2011: Annual mean of daily highs 62.4°F 2012: Annual mean of daily highs 66.2°F 2013: Annual mean of daily highs 60.4°F 2014: Annual mean of daily highs 58.3°F 2015: Annual mean of daily highs 62.3°F 2017: Annual mean of daily highs 64.0°F 2018: Annual mean of daily highs 61.7°F 2019: Annual mean of daily highs 61.2°F 2020: Annual mean of daily highs 62.2°F 2021: Annual mean of daily highs 62.7°F 2022: Annual mean of daily highs 62.0°F 2024: Annual mean of daily highs 64.3°F 2025: Annual mean of daily highs 62.7°F 2010: Annual mean of daily lows 44.2°F 2011: Annual mean of daily lows 45.0°F 2012: Annual mean of daily lows 46.0°F 2013: Annual mean of daily lows 42.5°F 2014: Annual mean of daily lows 40.6°F 2015: Annual mean of daily lows 44.2°F 2017: Annual mean of daily lows 45.8°F 2018: Annual mean of daily lows 44.4°F 2019: Annual mean of daily lows 44.1°F 2020: Annual mean of daily lows 45.1°F 2021: Annual mean of daily lows 45.3°F 2022: Annual mean of daily lows 43.4°F 2024: Annual mean of daily lows 46.1°F

Source: NOAA NCEI Global Summary of the Year.

Annual temperature data table (°F)
Annual station temperatures, 2010–2025. Unavailable means no reported value.
Year Annual mean (°F) Annual mean of daily highs (°F) Annual mean of daily lows (°F)
2010 53.1 62.1 44.2
2011 53.7 62.4 45.0
2012 56.1 66.2 46.0
2013 51.5 60.4 42.5
2014 49.4 58.3 40.6
2015 53.2 62.3 44.2
2016 Unavailable Unavailable Unavailable
2017 54.9 64.0 45.8
2018 53.0 61.7 44.4
2019 52.6 61.2 44.1
2020 53.7 62.2 45.1
2021 54.0 62.7 45.3
2022 52.7 62.0 43.4
2023 Unavailable Unavailable Unavailable
2024 55.2 64.3 46.1
2025 Unavailable 62.7 Unavailable
Source: NOAA NCEI 1991–2020 U.S. Climate Normals, National Weather Service.