La Grande, Oregon has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2 °C (low) to 16.1 °C (high). Annual precipitation averages 455.9 Millimeters. 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 | -4.2 °C | 3.5 °C | 47.5 mm |
| February | -3.3 °C | 6.1 °C | 31.75 mm |
| March | -1.3 °C | 10.8 °C | 43.18 mm |
| April | 0.9 °C | 14.6 °C | 46.23 mm |
| May | 4.6 °C | 19.7 °C | 53.34 mm |
| June | 7.5 °C | 23.7 °C | 38.1 mm |
| July | 10.1 °C | 30.2 °C | 12.45 mm |
| August | 9.4 °C | 30.4 °C | 16 mm |
| September | 5.6 °C | 25.2 °C | 15.75 mm |
| October | 1.2 °C | 16.9 °C | 35.56 mm |
| November | -1.6 °C | 8.4 °C | 55.37 mm |
| December | -4.4 °C | 3.3 °C | 60.71 mm |
| Annual | 2 °C | 16.1 °C | 455.94 mm |
| 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 : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |