Philomath, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.7 °C (low) to 17.3 °C (high). Annual precipitation averages 1097.5 Millimeters. Philomath 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 | 1.6 °C | 8.4 °C | 167.39 mm |
| February | 1.7 °C | 10.6 °C | 129.03 mm |
| March | 2.8 °C | 13.2 °C | 126.24 mm |
| April | 4.3 °C | 15.7 °C | 85.6 mm |
| May | 6.9 °C | 19.6 °C | 54.1 mm |
| June | 9.2 °C | 22.8 °C | 33.02 mm |
| July | 11.3 °C | 27.6 °C | 7.62 mm |
| August | 11.1 °C | 28 °C | 9.14 mm |
| September | 9.1 °C | 24.8 °C | 34.04 mm |
| October | 5.9 °C | 17.8 °C | 86.36 mm |
| November | 3.3 °C | 11.6 °C | 162.56 mm |
| December | 1.3 °C | 7.9 °C | 202.44 mm |
| Annual | 5.7 °C | 17.3 °C | 1097.54 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 |