Calhan, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.3 °C (low) to 16.3 °C (high). Annual precipitation averages 427 Millimeters. Calhan is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.7 °C | 5.8 °C | 9.65 mm |
| February | -8.8 °C | 6.3 °C | 10.41 mm |
| March | -4.9 °C | 10.9 °C | 27.43 mm |
| April | -1.3 °C | 14.3 °C | 47.5 mm |
| May | 3.7 °C | 19.3 °C | 56.64 mm |
| June | 8.9 °C | 25.8 °C | 47.24 mm |
| July | 12.3 °C | 28.8 °C | 68.33 mm |
| August | 11.5 °C | 27.3 °C | 78.49 mm |
| September | 6.8 °C | 23.7 °C | 29.46 mm |
| October | 0.4 °C | 16.9 °C | 28.96 mm |
| November | -5.3 °C | 10.4 °C | 12.45 mm |
| December | -9.5 °C | 5.7 °C | 10.41 mm |
| Annual | 0.3 °C | 16.3 °C | 426.97 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |