Millersburg, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 17.6 °C (high). Annual precipitation averages 1076.7 Millimeters. Millersburg is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.7 °C | 8.6 °C | 154.18 mm |
| February | 1.8 °C | 10.8 °C | 116.84 mm |
| March | 3 °C | 13.4 °C | 123.7 mm |
| April | 4.7 °C | 16.3 °C | 89.41 mm |
| May | 7.4 °C | 20.1 °C | 61.47 mm |
| June | 9.7 °C | 23 °C | 39.88 mm |
| July | 11.8 °C | 27.8 °C | 8.38 mm |
| August | 11.6 °C | 28.2 °C | 11.18 mm |
| September | 9.4 °C | 24.9 °C | 36.83 mm |
| October | 6.1 °C | 18.2 °C | 91.44 mm |
| November | 3.6 °C | 11.7 °C | 157.73 mm |
| December | 1.5 °C | 8.1 °C | 185.67 mm |
| Annual | 6 °C | 17.6 °C | 1076.71 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |