Seattle, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.2 °C (low) to 15.8 °C (high). Annual precipitation averages 983 Millimeters. Seattle is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.6 °C | 8.4 °C | 136.4 mm |
| February | 2.7 °C | 9.8 °C | 93.73 mm |
| March | 3.8 °C | 12 °C | 105.41 mm |
| April | 5.7 °C | 14.8 °C | 76.45 mm |
| May | 8.6 °C | 18.6 °C | 50.8 mm |
| June | 11 °C | 20.9 °C | 42.42 mm |
| July | 12.9 °C | 24.3 °C | 19.56 mm |
| August | 13.1 °C | 24.7 °C | 23.88 mm |
| September | 11.1 °C | 21.6 °C | 40.64 mm |
| October | 7.8 °C | 15.7 °C | 96.77 mm |
| November | 4.6 °C | 10.8 °C | 148.84 mm |
| December | 2.4 °C | 7.9 °C | 148.08 mm |
| Annual | 7.2 °C | 15.8 °C | 982.98 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°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 |