Grinnell Iowa Climate Data

Monthly Average Climate Data for Grinnell Iowa

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January12.4 °F28.6 °F1.05 in.
February16.1 °F33.1 °F1.44 in.
March26.8 °F46.1 °F2.15 in.
April37.9 °F60.1 °F3.94 in.
May50.7 °F70.8 °F5.02 in.
June60.6 °F80.2 °F5.45 in.
July64.6 °F83.7 °F4.21 in.
August61.8 °F81.8 °F4.41 in.
September53.0 °F75.9 °F3.66 in.
October41.0 °F62.9 °F2.92 in.
November29.0 °F47.3 °F2.0 in.
December18.6 °F34.2 °F1.55 in.
Annual39.4 °F58.7 °F37.8 in.

Climate Data for Grinnell Iowa

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