Mosier, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.2 °C (low) to 17.7 °C (high). Annual precipitation averages 736.6 Millimeters. Mosier is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.3 °C | 6.2 °C | 122.68 mm |
| February | 0.7 °C | 9.3 °C | 79.5 mm |
| March | 2.6 °C | 13.3 °C | 84.84 mm |
| April | 5.1 °C | 16.9 °C | 47.5 mm |
| May | 8.2 °C | 21.6 °C | 28.96 mm |
| June | 11.1 °C | 24.6 °C | 19.81 mm |
| July | 13.7 °C | 29.2 °C | 4.32 mm |
| August | 13.5 °C | 29.4 °C | 7.62 mm |
| September | 9.8 °C | 26.1 °C | 14.48 mm |
| October | 5.7 °C | 18.7 °C | 58.67 mm |
| November | 2.7 °C | 10.7 °C | 118.36 mm |
| December | 0.4 °C | 6.1 °C | 149.86 mm |
| Annual | 6.2 °C | 17.7 °C | 736.6 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |