Mossyrock, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 40.7 °F (low) to 61.2 °F (high). Annual precipitation averages 58.7 Inches. Mossyrock 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 33.0 °F | 45.3 °F | 8.18 in. |
| February | 33.0 °F | 49.3 °F | 5.8 in. |
| March | 35.1 °F | 53.9 °F | 6.31 in. |
| April | 38.1 °F | 59.8 °F | 5.37 in. |
| May | 43.5 °F | 67.3 °F | 3.7 in. |
| June | 47.6 °F | 71.6 °F | 2.68 in. |
| July | 51.1 °F | 79.4 °F | 0.88 in. |
| August | 51.0 °F | 79.5 °F | 1.18 in. |
| September | 46.8 °F | 73.4 °F | 2.34 in. |
| October | 40.9 °F | 60.4 °F | 5.44 in. |
| November | 35.9 °F | 50.4 °F | 8.53 in. |
| December | 32.6 °F | 44.2 °F | 8.27 in. |
| Annual | 40.7 °F | 61.2 °F | 58.68 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |