Fort Defiance, Arizona has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 1.1 °C (low) to 18.3 °C (high). Annual precipitation averages 283.5 Millimeters. Fort Defiance is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.6 °C | 6.8 °C | 17.02 mm |
| February | -6.4 °C | 8.8 °C | 15.75 mm |
| March | -4.1 °C | 13.1 °C | 17.78 mm |
| April | -0.7 °C | 17.2 °C | 12.7 mm |
| May | 3.8 °C | 22.2 °C | 14.99 mm |
| June | 8.7 °C | 28.7 °C | 8.13 mm |
| July | 12.9 °C | 30.3 °C | 41.91 mm |
| August | 12.2 °C | 28.6 °C | 52.07 mm |
| September | 7.9 °C | 25.4 °C | 38.1 mm |
| October | 0.9 °C | 19.5 °C | 24.13 mm |
| November | -4.6 °C | 12.4 °C | 20.32 mm |
| December | -8.3 °C | 7 °C | 20.57 mm |
| Annual | 1.1 °C | 18.3 °C | 283.47 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | 150-180 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 | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |