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Cass County, IL

: September 2026 so far averaged 74.4°F in Cass County, IL, the warmest 1 to 29 September in the county average since the data begin in 1951 (county average from NOAA gridded data, 1951 to 2026).

Last updated . This page normally updates every day; the latest update is late.

High
79.5°F
Warmest since 2025
24th warmest of 76
Low
48.8°F
Warmest since 2025
38th warmest of 76

No measurable precipitation in the county average of Cass County, IL for 2 days to Tuesday 29 September 2026 (county average from NOAA gridded data, 1951 to 2026).

Every 29 September high of the county average in Cass County, IL since 1951: 79.5°F in 2026; the highest is 97.9°F, in 1953.
2025: 89.7°F1953: 97.9°F2026: 79.5°F 2026 79.5°F 1953 97.9°F since 2025 1951 2026
  • Normal range, 63.5 to 82.7°F
Every year as a table

Every 29 September low of the county average in Cass County, IL since 1951: 48.8°F in 2026; the lowest is 35.1°F, in 1984.

YearHigh, °FLow, °F
202679.548.8
202589.753.7
202476.461.3
202376.255.1
202263.737.9
202188.557.5
202066.344.3
201982.863.6
201870.347.3
201774.946.3
201662.351.4
201581.360.4
201484.754.8
20138151
201270.843.9
201171.750.2
201075.447.5
200964.748
200879.454.9
200782.749.6
200663.541.2
200573.542.8
200472.740.3
200360.336.1
200281.653.1
200164.642.9
200073.746.4
199963.648.9
199883.161.6
199775.151.8
199669.243.6
199580.251.4
199472.344.9
199366.339.3
199263.237.4
199175.849
199076.957.3
19897540.5
198883.458.6
198782.356.6
198689.269.3
198575.848
198456.835.1
19838554.3
198279.656
198170.846.1
198076.744.9
19798656.6
197870.242.8
197773.948.6
197666.948.3
197570.148.7
197468.845.9
19738064.2
197278.548.3
197188.467.5
197072.344
196977.149.7
196875.249.7
196756.836.3
196669.750.9
196578.251.9
19646938.9
196378.347.1
196271.436.3
196168.440.3
196074.848.2
19597452.2
195870.242.3
195770.936.4
195685.154.1
195581.858.5
195483.864.5
195397.964.1
195288.954.5
195162.336.2

The month

August 2026 averaged 75°F in Cass County, IL, the warmest August in the county average since 2021, tied 50th warmest of 132 (with 1928, 1896 and 1895) (county average from NOAA's monthly county data, 1895 to 2026).

The month in words
  • Tuesday 29 September 2026: a high of 79.5°F averaged over Cass County, IL, the warmest 29 September in the county average since 2025, 24th warmest of 76 (county average from NOAA gridded data, 1951 to 2026).
  • Tuesday 29 September 2026: a low of 48.8°F averaged over Cass County, IL, the warmest 29 September night in the county average since 2025, 38th warmest of 76 (county average from NOAA gridded data, 1951 to 2026).
Days of the month without a value
0

Nearby

Springfield, IL 31.0 mi, the nearest city with its own station