Thermopolis, Wyoming has a Cold Desert Climate climate (Köppen classification: BWk). Average annual temperatures range from 30.8 °F (low) to 61.8 °F (high). Annual precipitation averages 12.6 Inches. Thermopolis is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.8 °F | 35.0 °F | 0.38 in. |
| February | 11.7 °F | 39.5 °F | 0.47 in. |
| March | 22.5 °F | 52.3 °F | 0.95 in. |
| April | 30.9 °F | 60.5 °F | 1.67 in. |
| May | 40.5 °F | 69.9 °F | 2.64 in. |
| June | 48.4 °F | 81.4 °F | 1.45 in. |
| July | 55.1 °F | 90.4 °F | 0.72 in. |
| August | 52.3 °F | 88.9 °F | 0.56 in. |
| September | 42.9 °F | 78.4 °F | 1.3 in. |
| October | 31.2 °F | 63.1 °F | 1.34 in. |
| November | 18.4 °F | 46.9 °F | 0.59 in. |
| December | 9.0 °F | 35.7 °F | 0.57 in. |
| Annual | 30.8 °F | 61.8 °F | 12.64 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 | BWk - Cold Desert Climate |