Pierson, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.6 °C (low) to 14.6 °C (high). Annual precipitation averages 796 Millimeters. Pierson is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.8 °C | -2.4 °C | 17.78 mm |
| February | -10.5 °C | 0.2 °C | 21.84 mm |
| March | -4.2 °C | 7.6 °C | 44.45 mm |
| April | 1.9 °C | 15.3 °C | 83.82 mm |
| May | 8.9 °C | 21.6 °C | 107.7 mm |
| June | 15.1 °C | 27.2 °C | 124.97 mm |
| July | 17 °C | 28.7 °C | 96.27 mm |
| August | 15.6 °C | 27.4 °C | 104.9 mm |
| September | 10.4 °C | 24.4 °C | 74.68 mm |
| October | 3.3 °C | 17 °C | 58.67 mm |
| November | -3.8 °C | 7.9 °C | 34.8 mm |
| December | -9.6 °C | 0.4 °C | 26.16 mm |
| Annual | 2.6 °C | 14.6 °C | 796.04 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |