Brinnon, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.4 °C (low) to 15.8 °C (high). Annual precipitation averages 1024.9 Millimeters. Brinnon 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.1 °C | 8.2 °C | 153.67 mm |
| February | 1.9 °C | 9.7 °C | 104.14 mm |
| March | 3.1 °C | 12.1 °C | 116.33 mm |
| April | 4.8 °C | 15.1 °C | 71.88 mm |
| May | 7.8 °C | 18.7 °C | 49.28 mm |
| June | 10.3 °C | 20.8 °C | 41.91 mm |
| July | 12.1 °C | 24.3 °C | 19.56 mm |
| August | 12.1 °C | 24.8 °C | 26.16 mm |
| September | 10.1 °C | 21.8 °C | 40.89 mm |
| October | 6.8 °C | 15.7 °C | 84.84 mm |
| November | 3.8 °C | 10.7 °C | 151.38 mm |
| December | 1.9 °C | 7.8 °C | 164.85 mm |
| Annual | 6.4 °C | 15.8 °C | 1024.89 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 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 |