Sedro-Woolley, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.7 °F (low) to 59.7 °F (high). Annual precipitation averages 46.6 Inches. Sedro-Woolley 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 | 35.0 °F | 46.4 °F | 5.93 in. |
| February | 34.8 °F | 48.6 °F | 3.95 in. |
| March | 37.5 °F | 52.6 °F | 4.65 in. |
| April | 40.8 °F | 58.2 °F | 4.05 in. |
| May | 45.6 °F | 64.9 °F | 3.18 in. |
| June | 49.9 °F | 69.0 °F | 2.55 in. |
| July | 52.3 °F | 74.6 °F | 1.22 in. |
| August | 52.1 °F | 75.6 °F | 1.45 in. |
| September | 48.6 °F | 69.7 °F | 2.8 in. |
| October | 42.8 °F | 59.9 °F | 4.72 in. |
| November | 38.3 °F | 51.0 °F | 6.98 in. |
| December | 34.5 °F | 45.4 °F | 5.16 in. |
| Annual | 42.7 °F | 59.7 °F | 46.64 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 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 |