Holly Hills, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 2.9 °C (low) to 18.3 °C (high). Annual precipitation averages 441.2 Millimeters. Holly Hills 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 | -7.1 °C | 7.8 °C | 14.48 mm |
| February | -6.4 °C | 8.3 °C | 16 mm |
| March | -2.2 °C | 13.1 °C | 38.61 mm |
| April | 1.3 °C | 16.2 °C | 55.63 mm |
| May | 6.4 °C | 21.1 °C | 61.98 mm |
| June | 11.8 °C | 27.8 °C | 46.74 mm |
| July | 15.3 °C | 31.3 °C | 51.56 mm |
| August | 14.2 °C | 30.1 °C | 52.32 mm |
| September | 9.4 °C | 25.8 °C | 41.66 mm |
| October | 2.5 °C | 18.4 °C | 29.72 mm |
| November | -2.8 °C | 12.2 °C | 17.53 mm |
| December | -7.2 °C | 7.3 °C | 14.99 mm |
| Annual | 2.9 °C | 18.3 °C | 441.22 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |