La Grande, Oregon has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 35.7 °F (low) to 60.9 °F (high). Annual precipitation averages 18 Inches. La Grande is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.4 °F | 38.3 °F | 1.87 in. |
| February | 26.0 °F | 43.0 °F | 1.25 in. |
| March | 29.6 °F | 51.5 °F | 1.7 in. |
| April | 33.6 °F | 58.3 °F | 1.82 in. |
| May | 40.3 °F | 67.4 °F | 2.1 in. |
| June | 45.5 °F | 74.7 °F | 1.5 in. |
| July | 50.2 °F | 86.4 °F | 0.49 in. |
| August | 48.9 °F | 86.8 °F | 0.63 in. |
| September | 42.0 °F | 77.3 °F | 0.62 in. |
| October | 34.2 °F | 62.4 °F | 1.4 in. |
| November | 29.1 °F | 47.1 °F | 2.18 in. |
| December | 24.0 °F | 38.0 °F | 2.39 in. |
| Annual | 35.7 °F | 60.9 °F | 17.95 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |