Jansen, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 35.6 °F (low) to 66.7 °F (high). Annual precipitation averages 16.4 Inches. Jansen is located in USDA Plant Hardiness Zone 6a. 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 | 17.5 °F | 47.8 °F | 0.53 in. |
| February | 19.6 °F | 50.2 °F | 0.54 in. |
| March | 26.1 °F | 57.7 °F | 1.12 in. |
| April | 33.0 °F | 64.0 °F | 1.52 in. |
| May | 42.2 °F | 73.2 °F | 1.68 in. |
| June | 51.5 °F | 83.7 °F | 1.44 in. |
| July | 56.5 °F | 87.3 °F | 2.88 in. |
| August | 54.9 °F | 85.0 °F | 2.72 in. |
| September | 47.5 °F | 79.2 °F | 1.42 in. |
| October | 35.6 °F | 68.4 °F | 1.12 in. |
| November | 25.5 °F | 56.3 °F | 0.76 in. |
| December | 17.6 °F | 47.4 °F | 0.64 in. |
| Annual | 35.6 °F | 66.7 °F | 16.37 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |