Williamson, Arizona has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 40.5 °F (low) to 71 °F (high). Annual precipitation averages 15.4 Inches. Williamson is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.8 °F | 53.0 °F | 1.61 in. |
| February | 27.1 °F | 55.9 °F | 1.6 in. |
| March | 31.8 °F | 62.0 °F | 1.4 in. |
| April | 36.9 °F | 68.3 °F | 0.52 in. |
| May | 44.5 °F | 76.6 °F | 0.46 in. |
| June | 53.1 °F | 87.4 °F | 0.26 in. |
| July | 60.9 °F | 90.2 °F | 2.33 in. |
| August | 59.7 °F | 88.2 °F | 2.43 in. |
| September | 52.3 °F | 83.1 °F | 1.74 in. |
| October | 40.7 °F | 73.5 °F | 0.86 in. |
| November | 30.4 °F | 62.2 °F | 0.79 in. |
| December | 24.1 °F | 52.1 °F | 1.36 in. |
| Annual | 40.5 °F | 71 °F | 15.36 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |