Ellensburg, Washington has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 36.8 °F (low) to 60.1 °F (high). Annual precipitation averages 9.2 Inches. Ellensburg is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.4 °F | 35.7 °F | 1.25 in. |
| February | 24.8 °F | 42.8 °F | 0.72 in. |
| March | 29.4 °F | 51.8 °F | 0.81 in. |
| April | 34.8 °F | 59.7 °F | 0.73 in. |
| May | 42.5 °F | 68.7 °F | 0.77 in. |
| June | 48.8 °F | 75.1 °F | 0.55 in. |
| July | 54.4 °F | 84.6 °F | 0.31 in. |
| August | 53.5 °F | 84.4 °F | 0.17 in. |
| September | 45.3 °F | 75.8 °F | 0.39 in. |
| October | 35.5 °F | 61.3 °F | 0.78 in. |
| November | 27.8 °F | 45.7 °F | 1.05 in. |
| December | 22.3 °F | 35.5 °F | 1.68 in. |
| Annual | 36.8 °F | 60.1 °F | 9.21 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |