Hartsel, Colorado has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 21.2 °F (low) to 54.3 °F (high). Annual precipitation averages 11.6 Inches. Hartsel is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around Jun. 21 - Jun. 30 through the first frost around Aug. 11 - Aug. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.6 °F | 34.9 °F | 0.42 in. |
| February | 4.9 °F | 36.5 °F | 0.29 in. |
| March | 13.4 °F | 43.9 °F | 0.78 in. |
| April | 20.3 °F | 50.2 °F | 0.97 in. |
| May | 28.3 °F | 60.2 °F | 1.06 in. |
| June | 35.5 °F | 71.7 °F | 0.86 in. |
| July | 41.3 °F | 76.8 °F | 2.07 in. |
| August | 39.9 °F | 74.1 °F | 2.23 in. |
| September | 32.1 °F | 68.0 °F | 1.25 in. |
| October | 21.4 °F | 56.5 °F | 0.77 in. |
| November | 12.2 °F | 44.5 °F | 0.38 in. |
| December | 2.5 °F | 34.7 °F | 0.49 in. |
| Annual | 21.2 °F | 54.3 °F | 11.57 in. |
| Average First Frost Date | Aug. 11 - Aug. 20 |
| Average Last Frost Date | Jun. 21 - Jun. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |