Coupeville, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 14.4 °C (high). Annual precipitation averages 575 Millimeters. Coupeville 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 | 2.2 °C | 7.9 °C | 70.1 mm |
| February | 1.9 °C | 9 °C | 52.07 mm |
| March | 3.1 °C | 11.1 °C | 53.85 mm |
| April | 4.7 °C | 13.7 °C | 48.51 mm |
| May | 7.4 °C | 16.7 °C | 42.67 mm |
| June | 9.6 °C | 18.9 °C | 34.54 mm |
| July | 10.9 °C | 21.6 °C | 18.8 mm |
| August | 10.9 °C | 22.1 °C | 16.76 mm |
| September | 9.1 °C | 19.6 °C | 30.48 mm |
| October | 6.2 °C | 14.6 °C | 54.61 mm |
| November | 3.7 °C | 10.4 °C | 83.31 mm |
| December | 2 °C | 7.6 °C | 69.34 mm |
| Annual | 6 °C | 14.4 °C | 575.04 mm |
| 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 : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |