Normal Illinois Climate Data

Monthly Average Climate Data for Normal Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January16.2 °F32.4 °F2.32 in.
February19.7 °F37.3 °F1.91 in.
March28.9 °F49.3 °F2.69 in.
April40.0 °F62.5 °F3.77 in.
May51.6 °F73.4 °F4.52 in.
June61.3 °F82.2 °F4.12 in.
July64.3 °F85.4 °F3.88 in.
August62.4 °F83.4 °F3.65 in.
September54.6 °F78.3 °F3.31 in.
October43.0 °F65.2 °F3.3 in.
November31.7 °F50.2 °F2.82 in.
December22.0 °F37.6 °F2.38 in.
Annual41.3 °F61.4 °F38.67 in.

Climate Data for Normal Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateMay 11 - May 20
Average Days With Frost125-150 Days
Plant Hardiness Zone - 2023Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012Zone 5b : -15°F to -10°F
Current Drought ConditionsNormal
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation