Cortland Illinois Climate Data

Monthly Average Climate Data for Cortland Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January12.7 °F28.5 °F1.72 in.
February16.3 °F32.8 °F1.75 in.
March26.2 °F45.0 °F2.22 in.
April36.6 °F58.5 °F3.46 in.
May48.5 °F70.0 °F4.89 in.
June58.4 °F79.6 °F4.5 in.
July62.2 °F82.6 °F3.85 in.
August60.0 °F80.7 °F3.93 in.
September51.7 °F74.8 °F3.38 in.
October39.9 °F62.0 °F3.0 in.
November29.3 °F46.8 °F2.39 in.
December18.9 °F34.0 °F2.0 in.
Annual38.4 °F57.9 °F37.09 in.

Climate Data for Cortland Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateMay 1 - May 10
Average Days With Frost125-150 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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