Harrisburg, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.3 °F (low) to 63.5 °F (high). Annual precipitation averages 41.7 Inches. Harrisburg is located in USDA Plant Hardiness Zone 8b. 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 | 35.0 °F | 47.3 °F | 6.1 in. |
| February | 35.1 °F | 51.1 °F | 4.86 in. |
| March | 37.1 °F | 55.9 °F | 5.26 in. |
| April | 39.9 °F | 60.5 °F | 3.43 in. |
| May | 44.5 °F | 67.3 °F | 2.35 in. |
| June | 48.5 °F | 73.3 °F | 1.3 in. |
| July | 52.2 °F | 82.4 °F | 0.33 in. |
| August | 52.0 °F | 83.0 °F | 0.4 in. |
| September | 48.2 °F | 77.2 °F | 1.33 in. |
| October | 42.4 °F | 64.4 °F | 3.2 in. |
| November | 38.0 °F | 52.8 °F | 5.94 in. |
| December | 34.6 °F | 46.3 °F | 7.2 in. |
| Annual | 42.3 °F | 63.5 °F | 41.7 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |