Copalis Beach, Washington has a Temperate Oceanic Climate climate (Köppen classification: Cfb). Average annual temperatures range from 44.4 °F (low) to 56.7 °F (high). Annual precipitation averages 89.3 Inches. Copalis Beach is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 38.4 °F | 48.1 °F | 13.76 in. |
| February | 37.7 °F | 50.0 °F | 8.44 in. |
| March | 39.2 °F | 52.2 °F | 10.49 in. |
| April | 41.6 °F | 54.7 °F | 7.45 in. |
| May | 46.0 °F | 58.5 °F | 3.6 in. |
| June | 49.9 °F | 61.8 °F | 3.41 in. |
| July | 52.9 °F | 64.5 °F | 1.31 in. |
| August | 52.9 °F | 66.1 °F | 1.87 in. |
| September | 50.3 °F | 65.4 °F | 3.01 in. |
| October | 45.3 °F | 59.5 °F | 8.6 in. |
| November | 40.8 °F | 52.4 °F | 13.79 in. |
| December | 37.8 °F | 47.7 °F | 13.54 in. |
| Annual | 44.4 °F | 56.7 °F | 89.27 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 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 | Abnormally Dry |
| Köppen Climate Classification | Cfb - Temperate Oceanic Climate |