Mammoth, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 28.1 °F (low) to 53.5 °F (high). Annual precipitation averages 15.2 Inches. Mammoth is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.8 °F | 30.6 °F | 0.87 in. |
| February | 12.1 °F | 34.1 °F | 0.74 in. |
| March | 19.7 °F | 42.6 °F | 1.12 in. |
| April | 26.2 °F | 50.6 °F | 1.45 in. |
| May | 34.3 °F | 60.4 °F | 1.91 in. |
| June | 41.5 °F | 70.0 °F | 1.96 in. |
| July | 47.5 °F | 81.1 °F | 1.27 in. |
| August | 45.9 °F | 80.2 °F | 1.1 in. |
| September | 38.7 °F | 69.8 °F | 1.24 in. |
| October | 29.0 °F | 54.2 °F | 1.36 in. |
| November | 19.0 °F | 38.9 °F | 1.2 in. |
| December | 11.4 °F | 29.7 °F | 0.95 in. |
| Annual | 28.1 °F | 53.5 °F | 15.17 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |