Mammoth, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.2 °C (low) to 12 °C (high). Annual precipitation averages 385.3 Millimeters. 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 | -11.2 °C | -0.8 °C | 22.1 mm |
| February | -11.1 °C | 1.2 °C | 18.8 mm |
| March | -6.8 °C | 5.9 °C | 28.45 mm |
| April | -3.2 °C | 10.3 °C | 36.83 mm |
| May | 1.3 °C | 15.8 °C | 48.51 mm |
| June | 5.3 °C | 21.1 °C | 49.78 mm |
| July | 8.6 °C | 27.3 °C | 32.26 mm |
| August | 7.7 °C | 26.8 °C | 27.94 mm |
| September | 3.7 °C | 21 °C | 31.5 mm |
| October | -1.7 °C | 12.3 °C | 34.54 mm |
| November | -7.2 °C | 3.8 °C | 30.48 mm |
| December | -11.4 °C | -1.3 °C | 24.13 mm |
| Annual | -2.2 °C | 12 °C | 385.32 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |