Umatilla, Oregon has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 42 °F (low) to 65.7 °F (high). Annual precipitation averages 9.1 Inches. Umatilla 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 | 28.8 °F | 42.1 °F | 1.19 in. |
| February | 29.3 °F | 48.0 °F | 0.88 in. |
| March | 33.9 °F | 57.6 °F | 0.85 in. |
| April | 39.9 °F | 65.4 °F | 0.71 in. |
| May | 47.5 °F | 74.4 °F | 0.89 in. |
| June | 53.6 °F | 81.1 °F | 0.63 in. |
| July | 59.3 °F | 90.7 °F | 0.17 in. |
| August | 58.5 °F | 89.8 °F | 0.22 in. |
| September | 50.0 °F | 80.4 °F | 0.38 in. |
| October | 40.4 °F | 65.8 °F | 0.82 in. |
| November | 33.3 °F | 50.9 °F | 1.03 in. |
| December | 28.9 °F | 41.6 °F | 1.32 in. |
| Annual | 42 °F | 65.7 °F | 9.09 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 7b : 5°F to 10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |