Castle Valley, Utah has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 41.2 °F (low) to 68.8 °F (high). Annual precipitation averages 11.4 Inches. Castle Valley is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 19.6 °F | 41.0 °F | 0.77 in. |
| February | 25.4 °F | 48.6 °F | 0.78 in. |
| March | 33.2 °F | 59.9 °F | 0.93 in. |
| April | 39.1 °F | 67.6 °F | 1.13 in. |
| May | 48.3 °F | 78.1 °F | 0.97 in. |
| June | 58.3 °F | 90.5 °F | 0.43 in. |
| July | 64.4 °F | 96.3 °F | 0.81 in. |
| August | 62.1 °F | 93.6 °F | 1.17 in. |
| September | 54.1 °F | 84.3 °F | 1.3 in. |
| October | 40.2 °F | 69.8 °F | 1.39 in. |
| November | 29.7 °F | 54.6 °F | 0.85 in. |
| December | 19.6 °F | 41.5 °F | 0.88 in. |
| Annual | 41.2 °F | 68.8 °F | 11.41 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |