Mukilteo, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.5 °C (low) to 15.6 °C (high). Annual precipitation averages 968.5 Millimeters. Mukilteo is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.1 °C | 8.2 °C | 124.21 mm |
| February | 2.2 °C | 9.7 °C | 89.41 mm |
| March | 3.3 °C | 11.9 °C | 106.17 mm |
| April | 5.2 °C | 14.8 °C | 81.03 mm |
| May | 7.9 °C | 18.4 °C | 58.17 mm |
| June | 10.2 °C | 20.6 °C | 52.07 mm |
| July | 11.8 °C | 23.7 °C | 23.11 mm |
| August | 11.8 °C | 24.1 °C | 23.62 mm |
| September | 9.9 °C | 21.3 °C | 43.18 mm |
| October | 6.9 °C | 15.7 °C | 92.71 mm |
| November | 4.1 °C | 10.7 °C | 146.3 mm |
| December | 2.1 °C | 7.7 °C | 128.52 mm |
| Annual | 6.5 °C | 15.6 °C | 968.5 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |