Lake Goodwin, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.5 °C (low) to 14.7 °C (high). Annual precipitation averages 1011.4 Millimeters. Lake Goodwin 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 | 1.9 °C | 7.4 °C | 126.24 mm |
| February | 1.9 °C | 8.8 °C | 88.39 mm |
| March | 3.3 °C | 10.9 °C | 111.76 mm |
| April | 5.2 °C | 13.8 °C | 81.03 mm |
| May | 7.9 °C | 17.4 °C | 64.52 mm |
| June | 10.1 °C | 19.5 °C | 49.53 mm |
| July | 12 °C | 22.9 °C | 26.67 mm |
| August | 12.3 °C | 23.5 °C | 26.42 mm |
| September | 10.4 °C | 20.6 °C | 50.8 mm |
| October | 7.1 °C | 14.7 °C | 96.27 mm |
| November | 3.8 °C | 9.9 °C | 153.67 mm |
| December | 1.8 °C | 7.2 °C | 136.14 mm |
| Annual | 6.5 °C | 14.7 °C | 1011.44 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 |