Brier, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 44 °F (low) to 59.7 °F (high). Annual precipitation averages 41.1 Inches. Brier is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.9 °F | 46.8 °F | 5.57 in. |
| February | 35.8 °F | 49.2 °F | 3.92 in. |
| March | 38.2 °F | 53.2 °F | 4.36 in. |
| April | 41.4 °F | 57.7 °F | 3.39 in. |
| May | 46.6 °F | 64.6 °F | 2.14 in. |
| June | 50.6 °F | 68.6 °F | 2.08 in. |
| July | 54.3 °F | 74.8 °F | 0.93 in. |
| August | 54.8 °F | 75.5 °F | 1.14 in. |
| September | 51.2 °F | 69.6 °F | 1.71 in. |
| October | 45.0 °F | 59.7 °F | 3.9 in. |
| November | 39.0 °F | 51.1 °F | 6.26 in. |
| December | 35.5 °F | 45.9 °F | 5.72 in. |
| Annual | 44 °F | 59.7 °F | 41.12 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |