Lake Forest Illinois Climate Data

Monthly Average Climate Data for Lake Forest Illinois

Switch Data to Fahrenheit
MonthAvg. LowAvg. HighAvg. Precip
January-8.4 °C-0.7 °C54.1 mm
February-6.8 °C1.3 °C52.32 mm
March-1.9 °C6.8 °C58.93 mm
April3.4 °C12.9 °C106.68 mm
May9.2 °C19.3 °C119.63 mm
June14.7 °C24.9 °C108.97 mm
July18.4 °C27.6 °C102.36 mm
August18.2 °C26.8 °C100.33 mm
September13.8 °C23.1 °C106.17 mm
October7.1 °C16.4 °C86.36 mm
November0.7 °C8.7 °C69.85 mm
December-5 °C2.3 °C53.09 mm
Annual5.3 °C14.1 °C1018.79 mm

Climate Data for Lake Forest Illinois

Average First Frost DateOct. 21 - Oct. 31
Average Last Frost DateMay 1 - May 10
Average Days With Frost100-125 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 ConditionsNormal
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation