Bristow, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37 °F (low) to 57 °F (high). Annual precipitation averages 36.1 Inches. Bristow 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 | 8.6 °F | 25.5 °F | 0.93 in. |
| February | 12.7 °F | 30.0 °F | 1.06 in. |
| March | 24.5 °F | 43.2 °F | 1.85 in. |
| April | 36.0 °F | 58.5 °F | 3.81 in. |
| May | 48.5 °F | 70.4 °F | 5.0 in. |
| June | 59.3 °F | 80.1 °F | 5.76 in. |
| July | 62.6 °F | 83.0 °F | 4.52 in. |
| August | 59.9 °F | 80.8 °F | 4.12 in. |
| September | 51.3 °F | 74.9 °F | 3.38 in. |
| October | 39.0 °F | 61.5 °F | 2.57 in. |
| November | 26.5 °F | 44.7 °F | 1.74 in. |
| December | 15.4 °F | 31.2 °F | 1.37 in. |
| Annual | 37 °F | 57 °F | 36.11 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |