Iroquois Illinois Climate Data

Monthly Average Climate Data for Iroquois Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January16.4 °F32.3 °F2.22 in.
February19.4 °F36.9 °F1.95 in.
March29.0 °F48.6 °F2.54 in.
April38.9 °F62.3 °F3.82 in.
May50.5 °F73.2 °F4.31 in.
June60.2 °F81.9 °F4.99 in.
July63.4 °F84.4 °F4.63 in.
August61.0 °F83.0 °F3.58 in.
September53.1 °F78.3 °F3.17 in.
October41.9 °F65.6 °F3.28 in.
November31.5 °F49.9 °F2.67 in.
December22.0 °F37.4 °F2.25 in.
Annual40.6 °F61.2 °F39.41 in.

Climate Data for Iroquois Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateMay 11 - May 20
Average Days With Frost100-125 Days
Plant Hardiness Zone - 2023Zone 5b : -15°F to -10°F
Plant Hardiness Zone - 2012Zone 5b : -15°F to -10°F
Current Drought ConditionsAbnormally Dry
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation
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