Tri-City, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.2 °F (low) to 67.5 °F (high). Annual precipitation averages 34.6 Inches. Tri-City 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.4 °F | 49.4 °F | 5.34 in. |
| February | 34.9 °F | 54.0 °F | 3.78 in. |
| March | 36.6 °F | 58.7 °F | 3.71 in. |
| April | 39.5 °F | 64.5 °F | 3.09 in. |
| May | 44.5 °F | 72.6 °F | 2.2 in. |
| June | 48.9 °F | 79.3 °F | 0.99 in. |
| July | 53.4 °F | 88.2 °F | 0.27 in. |
| August | 52.4 °F | 88.6 °F | 0.32 in. |
| September | 47.4 °F | 82.6 °F | 0.8 in. |
| October | 41.5 °F | 69.4 °F | 2.26 in. |
| November | 38.1 °F | 55.1 °F | 4.91 in. |
| December | 34.3 °F | 47.6 °F | 6.93 in. |
| Annual | 42.2 °F | 67.5 °F | 34.6 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 30-40 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 |