Grinnell, Kansas has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.7 °F (low) to 66.4 °F (high). Annual precipitation averages 21.6 Inches. Grinnell is located in USDA Plant Hardiness Zone 6a. 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 | 16.5 °F | 42.7 °F | 0.4 in. |
| February | 19.0 °F | 45.9 °F | 0.61 in. |
| March | 26.9 °F | 56.2 °F | 1.15 in. |
| April | 35.7 °F | 64.7 °F | 1.93 in. |
| May | 47.2 °F | 74.4 °F | 3.25 in. |
| June | 58.1 °F | 86.0 °F | 2.85 in. |
| July | 63.4 °F | 90.9 °F | 3.67 in. |
| August | 61.5 °F | 88.3 °F | 2.99 in. |
| September | 52.3 °F | 80.9 °F | 1.71 in. |
| October | 38.8 °F | 68.0 °F | 1.66 in. |
| November | 26.7 °F | 54.5 °F | 0.7 in. |
| December | 18.1 °F | 43.8 °F | 0.66 in. |
| Annual | 38.7 °F | 66.4 °F | 21.58 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |