Jansen, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 2 °C (low) to 19.3 °C (high). Annual precipitation averages 415.8 Millimeters. 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 | -8.1 °C | 8.8 °C | 13.46 mm |
| February | -6.9 °C | 10.1 °C | 13.72 mm |
| March | -3.3 °C | 14.3 °C | 28.45 mm |
| April | 0.6 °C | 17.8 °C | 38.61 mm |
| May | 5.7 °C | 22.9 °C | 42.67 mm |
| June | 10.8 °C | 28.7 °C | 36.58 mm |
| July | 13.6 °C | 30.7 °C | 73.15 mm |
| August | 12.7 °C | 29.4 °C | 69.09 mm |
| September | 8.6 °C | 26.2 °C | 36.07 mm |
| October | 2 °C | 20.2 °C | 28.45 mm |
| November | -3.6 °C | 13.5 °C | 19.3 mm |
| December | -8 °C | 8.6 °C | 16.26 mm |
| Annual | 2 °C | 19.3 °C | 415.81 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |