Castle Dale, Utah has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33 °F (low) to 63.6 °F (high). Annual precipitation averages 7.9 Inches. Castle Dale is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.9 °F | 37.5 °F | 0.63 in. |
| February | 18.0 °F | 43.2 °F | 0.66 in. |
| March | 25.8 °F | 54.5 °F | 0.58 in. |
| April | 31.7 °F | 62.5 °F | 0.47 in. |
| May | 40.0 °F | 71.8 °F | 0.63 in. |
| June | 48.1 °F | 83.1 °F | 0.5 in. |
| July | 55.1 °F | 89.5 °F | 0.53 in. |
| August | 53.3 °F | 87.1 °F | 0.83 in. |
| September | 44.5 °F | 78.9 °F | 1.05 in. |
| October | 32.9 °F | 66.0 °F | 1.02 in. |
| November | 21.8 °F | 50.5 °F | 0.5 in. |
| December | 13.2 °F | 38.0 °F | 0.48 in. |
| Annual | 33 °F | 63.6 °F | 7.88 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |