Wallula, Washington has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 42.9 °F (low) to 65.3 °F (high). Annual precipitation averages 8.7 Inches. Wallula is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 29.6 °F | 41.9 °F | 1.16 in. |
| February | 31.0 °F | 47.9 °F | 0.84 in. |
| March | 35.7 °F | 57.4 °F | 0.76 in. |
| April | 41.0 °F | 65.1 °F | 0.73 in. |
| May | 48.0 °F | 74.1 °F | 0.87 in. |
| June | 54.0 °F | 80.8 °F | 0.67 in. |
| July | 59.5 °F | 90.1 °F | 0.2 in. |
| August | 58.6 °F | 88.9 °F | 0.23 in. |
| September | 50.9 °F | 79.6 °F | 0.29 in. |
| October | 41.9 °F | 65.3 °F | 0.75 in. |
| November | 34.7 °F | 50.8 °F | 0.99 in. |
| December | 29.6 °F | 41.5 °F | 1.19 in. |
| Annual | 42.9 °F | 65.3 °F | 8.68 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |