Normal Illinois Climate Data

Monthly Average Climate Data for Normal Illinois

Switch Data to Fahrenheit
MonthAvg. LowAvg. HighAvg. Precip
January-8.8 °C0.2 °C58.93 mm
February-6.8 °C2.9 °C48.51 mm
March-1.7 °C9.6 °C68.33 mm
April4.4 °C16.9 °C95.76 mm
May10.9 °C23 °C114.81 mm
June16.3 °C27.9 °C104.65 mm
July17.9 °C29.7 °C98.55 mm
August16.9 °C28.6 °C92.71 mm
September12.6 °C25.7 °C84.07 mm
October6.1 °C18.4 °C83.82 mm
November-0.2 °C10.1 °C71.63 mm
December-5.6 °C3.1 °C60.45 mm
Annual5.2 °C16.3 °C982.22 mm

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 : -23.3°C to -20.6°C
Plant Hardiness Zone - 2012Zone 5b : -26.1°C to -23.3°C
Current Drought ConditionsAbnormally Dry
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation