Alta, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 26.1 °F (low) to 52.1 °F (high). Annual precipitation averages 25.4 Inches. Alta is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °F | 28.5 °F | 2.6 in. |
| February | 9.9 °F | 32.1 °F | 1.93 in. |
| March | 17.6 °F | 40.5 °F | 2.21 in. |
| April | 25.1 °F | 48.8 °F | 2.42 in. |
| May | 33.2 °F | 59.5 °F | 2.97 in. |
| June | 39.8 °F | 68.7 °F | 2.27 in. |
| July | 45.4 °F | 79.2 °F | 1.36 in. |
| August | 43.6 °F | 78.3 °F | 1.3 in. |
| September | 36.4 °F | 68.7 °F | 1.82 in. |
| October | 27.7 °F | 53.5 °F | 2.11 in. |
| November | 17.3 °F | 38.6 °F | 2.04 in. |
| December | 8.8 °F | 28.4 °F | 2.4 in. |
| Annual | 26.1 °F | 52.1 °F | 25.43 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | Jun. 11 - Jun. 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 | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |