Blairstown, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.4 °F (low) to 58.7 °F (high). Annual precipitation averages 36.9 Inches. Blairstown 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.3 °F | 28.1 °F | 1.13 in. |
| February | 14.9 °F | 32.8 °F | 1.28 in. |
| March | 26.2 °F | 46.0 °F | 2.11 in. |
| April | 37.3 °F | 60.2 °F | 3.71 in. |
| May | 49.6 °F | 71.2 °F | 4.72 in. |
| June | 60.1 °F | 80.6 °F | 5.35 in. |
| July | 63.4 °F | 83.9 °F | 4.22 in. |
| August | 60.7 °F | 82.1 °F | 4.24 in. |
| September | 51.9 °F | 75.9 °F | 3.62 in. |
| October | 39.9 °F | 62.8 °F | 2.85 in. |
| November | 27.8 °F | 47.1 °F | 2.11 in. |
| December | 17.5 °F | 33.7 °F | 1.58 in. |
| Annual | 38.4 °F | 58.7 °F | 36.92 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |