Boulder, Wyoming has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 20.3 °F (low) to 52.6 °F (high). Annual precipitation averages 9.8 Inches. Boulder is located in USDA Plant Hardiness Zone 3b. The growing season typically runs from the last frost around Jun. 21 - Jun. 30 through the first frost around Aug. 1 - Aug. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.6 °F | 26.9 °F | 0.53 in. |
| February | -0.3 °F | 29.6 °F | 0.56 in. |
| March | 12.2 °F | 40.0 °F | 0.56 in. |
| April | 21.6 °F | 50.8 °F | 0.89 in. |
| May | 29.6 °F | 60.9 °F | 1.47 in. |
| June | 36.7 °F | 71.1 °F | 1.25 in. |
| July | 41.9 °F | 80.0 °F | 0.73 in. |
| August | 39.7 °F | 78.9 °F | 0.8 in. |
| September | 32.0 °F | 69.7 °F | 1.04 in. |
| October | 22.4 °F | 55.9 °F | 0.9 in. |
| November | 10.7 °F | 39.8 °F | 0.49 in. |
| December | -0.5 °F | 28.1 °F | 0.56 in. |
| Annual | 20.3 °F | 52.6 °F | 9.78 in. |
| Average First Frost Date | Aug. 1 - Aug. 10 |
| Average Last Frost Date | Jun. 21 - Jun. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3b : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |