Boulder Flats, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.6 °F (low) to 58.5 °F (high). Annual precipitation averages 13.1 Inches. Boulder Flats is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °F | 33.6 °F | 0.48 in. |
| February | 11.0 °F | 37.6 °F | 0.65 in. |
| March | 21.2 °F | 48.5 °F | 1.07 in. |
| April | 28.6 °F | 56.6 °F | 1.97 in. |
| May | 37.8 °F | 65.5 °F | 2.8 in. |
| June | 45.5 °F | 77.0 °F | 1.21 in. |
| July | 52.4 °F | 86.4 °F | 0.7 in. |
| August | 50.5 °F | 84.8 °F | 0.67 in. |
| September | 42.1 °F | 74.3 °F | 1.16 in. |
| October | 30.6 °F | 59.7 °F | 1.29 in. |
| November | 18.6 °F | 44.6 °F | 0.69 in. |
| December | 9.2 °F | 33.8 °F | 0.45 in. |
| Annual | 29.6 °F | 58.5 °F | 13.14 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |