Bar Nunn, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.2 °F (low) to 60 °F (high). Annual precipitation averages 15 Inches. Bar Nunn 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 | 16.2 °F | 36.8 °F | 0.61 in. |
| February | 17.0 °F | 38.6 °F | 0.79 in. |
| March | 24.2 °F | 48.9 °F | 1.21 in. |
| April | 30.2 °F | 56.4 °F | 1.89 in. |
| May | 39.2 °F | 66.2 °F | 2.75 in. |
| June | 47.9 °F | 78.9 °F | 1.52 in. |
| July | 55.1 °F | 88.0 °F | 1.17 in. |
| August | 53.0 °F | 86.3 °F | 0.89 in. |
| September | 43.4 °F | 75.7 °F | 1.11 in. |
| October | 32.6 °F | 60.3 °F | 1.6 in. |
| November | 23.3 °F | 46.7 °F | 0.78 in. |
| December | 16.4 °F | 36.8 °F | 0.71 in. |
| Annual | 33.2 °F | 60 °F | 15.03 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 5a : -20°F to -15°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |