Spanaway, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.3 °F (low) to 60.5 °F (high). Annual precipitation averages 43.7 Inches. Spanaway 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 | 34.4 °F | 46.7 °F | 6.2 in. |
| February | 34.1 °F | 49.4 °F | 4.09 in. |
| March | 36.3 °F | 53.6 °F | 4.82 in. |
| April | 39.4 °F | 58.3 °F | 3.52 in. |
| May | 45.0 °F | 65.3 °F | 2.32 in. |
| June | 49.6 °F | 69.7 °F | 1.85 in. |
| July | 53.0 °F | 76.6 °F | 0.75 in. |
| August | 53.1 °F | 77.4 °F | 1.08 in. |
| September | 48.8 °F | 71.5 °F | 1.7 in. |
| October | 42.7 °F | 60.3 °F | 4.53 in. |
| November | 37.3 °F | 51.2 °F | 6.67 in. |
| December | 33.9 °F | 45.7 °F | 6.2 in. |
| Annual | 42.3 °F | 60.5 °F | 43.73 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 |