Castle Dale, Utah has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 17.5 °C (high). Annual precipitation averages 200.1 Millimeters. 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 | -11.2 °C | 3.1 °C | 16 mm |
| February | -7.8 °C | 6.2 °C | 16.76 mm |
| March | -3.4 °C | 12.5 °C | 14.73 mm |
| April | -0.2 °C | 16.9 °C | 11.94 mm |
| May | 4.4 °C | 22.1 °C | 16 mm |
| June | 8.9 °C | 28.4 °C | 12.7 mm |
| July | 12.8 °C | 31.9 °C | 13.46 mm |
| August | 11.8 °C | 30.6 °C | 21.08 mm |
| September | 6.9 °C | 26.1 °C | 26.67 mm |
| October | 0.5 °C | 18.9 °C | 25.91 mm |
| November | -5.7 °C | 10.3 °C | 12.7 mm |
| December | -10.4 °C | 3.3 °C | 12.19 mm |
| Annual | 0.6 °C | 17.5 °C | 200.14 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |