Tonasket, Washington has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 38.6 °F (low) to 61.8 °F (high). Annual precipitation averages 12.7 Inches. Tonasket is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.8 °F | 34.2 °F | 1.18 in. |
| February | 25.7 °F | 41.5 °F | 0.89 in. |
| March | 31.2 °F | 53.2 °F | 0.99 in. |
| April | 37.0 °F | 63.7 °F | 0.95 in. |
| May | 44.5 °F | 73.3 °F | 1.49 in. |
| June | 50.9 °F | 79.6 °F | 1.45 in. |
| July | 56.4 °F | 88.7 °F | 0.63 in. |
| August | 55.4 °F | 88.0 °F | 0.54 in. |
| September | 46.8 °F | 77.6 °F | 0.53 in. |
| October | 37.5 °F | 61.5 °F | 1.03 in. |
| November | 29.9 °F | 45.1 °F | 1.34 in. |
| December | 24.5 °F | 34.8 °F | 1.67 in. |
| Annual | 38.6 °F | 61.8 °F | 12.69 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |