Ollie, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.6 °C (low) to 15.9 °C (high). Annual precipitation averages 966.7 Millimeters. Ollie is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | -0.5 °C | 33.02 mm |
| February | -8.1 °C | 2.1 °C | 40.13 mm |
| March | -2.1 °C | 9.3 °C | 57.91 mm |
| April | 4.1 °C | 16.7 °C | 95.76 mm |
| May | 10.7 °C | 22.3 °C | 130.81 mm |
| June | 16.3 °C | 27.6 °C | 133.1 mm |
| July | 18.2 °C | 29.6 °C | 105.92 mm |
| August | 16.8 °C | 28.6 °C | 107.44 mm |
| September | 11.9 °C | 25 °C | 91.95 mm |
| October | 5.3 °C | 17.9 °C | 72.64 mm |
| November | -1.1 °C | 9.4 °C | 56.39 mm |
| December | -6.8 °C | 2.4 °C | 41.66 mm |
| Annual | 4.6 °C | 15.9 °C | 966.73 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |