Mill City, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 41.8 °F (low) to 61.3 °F (high). Annual precipitation averages 65.4 Inches. Mill 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 | 33.6 °F | 46.0 °F | 8.45 in. |
| February | 34.1 °F | 49.3 °F | 6.64 in. |
| March | 36.4 °F | 53.6 °F | 7.57 in. |
| April | 39.4 °F | 58.6 °F | 6.4 in. |
| May | 44.1 °F | 65.5 °F | 4.56 in. |
| June | 48.7 °F | 71.2 °F | 2.88 in. |
| July | 52.4 °F | 79.7 °F | 0.59 in. |
| August | 52.1 °F | 80.7 °F | 0.71 in. |
| September | 47.6 °F | 74.2 °F | 2.52 in. |
| October | 42.5 °F | 61.9 °F | 5.66 in. |
| November | 37.3 °F | 50.6 °F | 9.11 in. |
| December | 33.5 °F | 44.8 °F | 10.29 in. |
| Annual | 41.8 °F | 61.3 °F | 65.38 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 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 | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |