Monticello Illinois Climate Data

Monthly Average Climate Data for Monticello Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January18.0 °F34.0 °F2.33 in.
February21.0 °F38.6 °F1.97 in.
March30.2 °F50.1 °F2.76 in.
April40.9 °F63.7 °F4.09 in.
May52.7 °F74.0 °F4.67 in.
June61.7 °F82.7 °F4.61 in.
July64.6 °F85.0 °F3.98 in.
August62.1 °F83.2 °F3.24 in.
September54.8 °F79.1 °F3.08 in.
October42.8 °F66.1 °F3.34 in.
November32.3 °F51.3 °F2.99 in.
December23.8 °F38.8 °F2.34 in.
Annual42.1 °F62.2 °F39.4 in.

Climate Data for Monticello Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateApr. 21 - Apr. 30
Average Days With Frost100-125 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
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