Shelby, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.7 °F (low) to 59.6 °F (high). Annual precipitation averages 34.1 Inches. Shelby is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.6 °F | 29.9 °F | 0.79 in. |
| February | 15.8 °F | 34.7 °F | 1.03 in. |
| March | 26.6 °F | 48.0 °F | 1.86 in. |
| April | 37.5 °F | 60.9 °F | 3.51 in. |
| May | 49.9 °F | 71.3 °F | 5.11 in. |
| June | 60.3 °F | 81.0 °F | 5.07 in. |
| July | 64.0 °F | 84.3 °F | 3.84 in. |
| August | 61.2 °F | 82.2 °F | 4.08 in. |
| September | 52.0 °F | 76.4 °F | 3.35 in. |
| October | 40.1 °F | 63.9 °F | 2.65 in. |
| November | 27.4 °F | 47.6 °F | 1.5 in. |
| December | 17.7 °F | 35.0 °F | 1.3 in. |
| Annual | 38.7 °F | 59.6 °F | 34.09 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°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 |