Dillon, Colorado has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 22.3 °F (low) to 51.9 °F (high). Annual precipitation averages 15.6 Inches. Dillon is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 21 - Jun. 30 through the first frost around July 21 - July 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.8 °F | 31.8 °F | 1.07 in. |
| February | 6.9 °F | 34.1 °F | 1.09 in. |
| March | 13.5 °F | 41.6 °F | 1.24 in. |
| April | 20.5 °F | 48.0 °F | 1.57 in. |
| May | 28.4 °F | 57.9 °F | 1.4 in. |
| June | 35.1 °F | 69.4 °F | 1.11 in. |
| July | 40.9 °F | 74.8 °F | 1.85 in. |
| August | 39.5 °F | 72.5 °F | 1.89 in. |
| September | 32.7 °F | 66.1 °F | 1.43 in. |
| October | 23.9 °F | 53.8 °F | 1.03 in. |
| November | 14.0 °F | 40.9 °F | 0.96 in. |
| December | 5.9 °F | 31.8 °F | 0.98 in. |
| Annual | 22.3 °F | 51.9 °F | 15.62 in. |
| Average First Frost Date | July 21 - July 31 |
| Average Last Frost Date | Jun. 21 - Jun. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Exceptional Drought |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |