Thermopolis, Wyoming has a Cold Desert Climate climate (Köppen classification: BWk). Average annual temperatures range from -0.7 °C (low) to 16.6 °C (high). Annual precipitation averages 321.1 Millimeters. 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 | -14 °C | 1.7 °C | 9.65 mm |
| February | -11.3 °C | 4.2 °C | 11.94 mm |
| March | -5.3 °C | 11.3 °C | 24.13 mm |
| April | -0.6 °C | 15.8 °C | 42.42 mm |
| May | 4.7 °C | 21.1 °C | 67.06 mm |
| June | 9.1 °C | 27.4 °C | 36.83 mm |
| July | 12.8 °C | 32.4 °C | 18.29 mm |
| August | 11.3 °C | 31.6 °C | 14.22 mm |
| September | 6.1 °C | 25.8 °C | 33.02 mm |
| October | -0.4 °C | 17.3 °C | 34.04 mm |
| November | -7.6 °C | 8.3 °C | 14.99 mm |
| December | -12.8 °C | 2.1 °C | 14.48 mm |
| Annual | -0.7 °C | 16.6 °C | 321.07 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BWk - Cold Desert Climate |