Brush Prairie, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 16.7 °C (high). Annual precipitation averages 1253 Millimeters. Brush Prairie 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.3 °C | 8.1 °C | 175.77 mm |
| February | 1.3 °C | 10.3 °C | 129.29 mm |
| March | 2.8 °C | 12.8 °C | 135.13 mm |
| April | 4.6 °C | 15.5 °C | 106.43 mm |
| May | 7.7 °C | 19.3 °C | 79.25 mm |
| June | 9.9 °C | 21.9 °C | 55.88 mm |
| July | 12.2 °C | 26.1 °C | 14.22 mm |
| August | 12.1 °C | 26.7 °C | 18.29 mm |
| September | 9.7 °C | 23.7 °C | 53.09 mm |
| October | 6.2 °C | 17.3 °C | 116.84 mm |
| November | 3.3 °C | 11.3 °C | 177.8 mm |
| December | 1.2 °C | 7.6 °C | 191.01 mm |
| Annual | 6 °C | 16.7 °C | 1253 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |