Fontenelle, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 24.5 °F (low) to 54.8 °F (high). Annual precipitation averages 7.6 Inches. Fontenelle is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.1 °F | 29.3 °F | 0.34 in. |
| February | 5.8 °F | 32.5 °F | 0.33 in. |
| March | 17.0 °F | 43.1 °F | 0.53 in. |
| April | 24.8 °F | 52.6 °F | 0.84 in. |
| May | 33.2 °F | 62.6 °F | 1.49 in. |
| June | 40.3 °F | 73.7 °F | 0.76 in. |
| July | 46.5 °F | 82.5 °F | 0.46 in. |
| August | 44.3 °F | 81.0 °F | 0.7 in. |
| September | 35.5 °F | 71.4 °F | 0.86 in. |
| October | 25.3 °F | 56.9 °F | 0.65 in. |
| November | 14.8 °F | 42.0 °F | 0.32 in. |
| December | 4.4 °F | 30.2 °F | 0.29 in. |
| Annual | 24.5 °F | 54.8 °F | 7.57 in. |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | Jun. 11 - Jun. 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |