Portsmouth Iowa Climate Data

Monthly Average Climate Data for Portsmouth Iowa

Switch Data to Fahrenheit
MonthAvg. LowAvg. HighAvg. Precip
January-11.5 °C-1.1 °C19.81 mm
February-9.2 °C1.6 °C25.65 mm
March-3.1 °C9.1 °C47.24 mm
April2.9 °C16.3 °C88.65 mm
May9.8 °C22.1 °C124.97 mm
June15.7 °C27.6 °C126.75 mm
July17.8 °C29.3 °C96.52 mm
August16.2 °C28.2 °C105.92 mm
September11.1 °C24.9 °C86.11 mm
October4.3 °C17.9 °C66.04 mm
November-2.8 °C8.8 °C37.08 mm
December-8.3 °C1.6 °C32.51 mm
Annual3.6 °C15.5 °C857.25 mm

Climate Data for Portsmouth Iowa

Average First Frost DateOct. 1 - Oct. 10
Average Last Frost DateMay 11 - May 20
Average Days With Frost125-150 Days
Plant Hardiness Zone - 2023Zone 5b : -26.1°C to -23.3°C
Plant Hardiness Zone - 2012Zone 5a : -28.9°C to -26.1°C
Current Drought ConditionsModerate Drought
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation
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