Boulder, Wyoming has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from -6.5 °C (low) to 11.5 °C (high). Annual precipitation averages 248.4 Millimeters. 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 | -19.2 °C | -2.8 °C | 13.46 mm |
| February | -17.9 °C | -1.3 °C | 14.22 mm |
| March | -11 °C | 4.4 °C | 14.22 mm |
| April | -5.8 °C | 10.4 °C | 22.61 mm |
| May | -1.3 °C | 16.1 °C | 37.34 mm |
| June | 2.6 °C | 21.7 °C | 31.75 mm |
| July | 5.5 °C | 26.7 °C | 18.54 mm |
| August | 4.3 °C | 26.1 °C | 20.32 mm |
| September | 0 °C | 20.9 °C | 26.42 mm |
| October | -5.3 °C | 13.3 °C | 22.86 mm |
| November | -11.8 °C | 4.3 °C | 12.45 mm |
| December | -18.1 °C | -2.2 °C | 14.22 mm |
| Annual | -6.5 °C | 11.5 °C | 248.41 mm |
| 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 : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |