Yarnell, Arizona has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 8.2 °C (low) to 22.8 °C (high). Annual precipitation averages 554.7 Millimeters. Yarnell is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Jan. 21 - Jan. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.2 °C | 13.2 °C | 56.13 mm |
| February | 1.1 °C | 14.2 °C | 76.96 mm |
| March | 2.7 °C | 17.1 °C | 55.37 mm |
| April | 5.6 °C | 20.9 °C | 18.03 mm |
| May | 9.9 °C | 25.8 °C | 7.37 mm |
| June | 14.9 °C | 31.6 °C | 4.83 mm |
| July | 18.6 °C | 33.4 °C | 57.91 mm |
| August | 18 °C | 32.4 °C | 103.38 mm |
| September | 15 °C | 29.8 °C | 69.6 mm |
| October | 9.3 °C | 24.2 °C | 21.59 mm |
| November | 3.5 °C | 17.7 °C | 32.51 mm |
| December | 0.1 °C | 12.7 °C | 51.05 mm |
| Annual | 8.2 °C | 22.8 °C | 554.73 mm |
| Average First Frost Date | Jan. 21 - Jan. 31 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |