Kapowsin, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 41.7 °F (low) to 60.1 °F (high). Annual precipitation averages 45 Inches. Kapowsin 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 | 33.8 °F | 45.8 °F | 6.17 in. |
| February | 33.6 °F | 48.5 °F | 4.17 in. |
| March | 35.7 °F | 52.8 °F | 5.23 in. |
| April | 38.8 °F | 58.0 °F | 3.72 in. |
| May | 44.3 °F | 65.2 °F | 2.92 in. |
| June | 48.8 °F | 69.6 °F | 2.37 in. |
| July | 52.3 °F | 76.7 °F | 0.95 in. |
| August | 52.5 °F | 77.7 °F | 1.21 in. |
| September | 48.3 °F | 71.7 °F | 1.63 in. |
| October | 42.1 °F | 60.3 °F | 4.47 in. |
| November | 36.8 °F | 50.4 °F | 6.64 in. |
| December | 33.2 °F | 44.7 °F | 5.56 in. |
| Annual | 41.7 °F | 60.1 °F | 45.04 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |