Ottawa Illinois Climate Data

Monthly Average Climate Data for Ottawa Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January15.6 °F31.7 °F1.98 in.
February19.0 °F36.1 °F1.89 in.
March28.4 °F48.4 °F2.5 in.
April39.1 °F61.6 °F3.51 in.
May50.4 °F72.6 °F4.71 in.
June60.1 °F81.4 °F4.6 in.
July63.8 °F84.4 °F3.85 in.
August61.8 °F82.6 °F3.9 in.
September54.0 °F77.2 °F3.32 in.
October42.5 °F64.7 °F3.1 in.
November31.7 °F49.8 °F2.7 in.
December21.5 °F36.9 °F2.12 in.
Annual40.7 °F60.6 °F38.18 in.

Climate Data for Ottawa 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 ConditionsNormal
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation