Heppner, Oregon has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 3.5 °C (low) to 16.8 °C (high). Annual precipitation averages 338.1 Millimeters. Heppner 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.9 °C | 5.6 °C | 32 mm |
| February | -2.1 °C | 7.9 °C | 27.94 mm |
| March | 0.1 °C | 12 °C | 35.31 mm |
| April | 2.3 °C | 15.4 °C | 39.37 mm |
| May | 5.8 °C | 20.2 °C | 44.2 mm |
| June | 8.6 °C | 24.2 °C | 35.56 mm |
| July | 11.6 °C | 29.9 °C | 7.87 mm |
| August | 11.3 °C | 29.7 °C | 7.11 mm |
| September | 7.8 °C | 24.7 °C | 10.92 mm |
| October | 3.3 °C | 17.2 °C | 29.97 mm |
| November | -0.3 °C | 10 °C | 35.81 mm |
| December | -3.2 °C | 5.1 °C | 32 mm |
| Annual | 3.5 °C | 16.8 °C | 338.06 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |