Big Lake, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.9 °C (low) to 15.4 °C (high). Annual precipitation averages 1002.3 Millimeters. Big Lake 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 | 1.5 °C | 7.8 °C | 126.24 mm |
| February | 1.4 °C | 9.1 °C | 88.9 mm |
| March | 2.9 °C | 11.4 °C | 99.06 mm |
| April | 4.8 °C | 14.8 °C | 81.28 mm |
| May | 7.6 °C | 18.4 °C | 72.64 mm |
| June | 9.9 °C | 20.6 °C | 50.8 mm |
| July | 11.4 °C | 23.9 °C | 25.65 mm |
| August | 11.4 °C | 24.4 °C | 31.24 mm |
| September | 9.4 °C | 21.2 °C | 54.36 mm |
| October | 6.1 °C | 15.6 °C | 106.68 mm |
| November | 3.4 °C | 10.4 °C | 147.32 mm |
| December | 1.3 °C | 7.3 °C | 118.11 mm |
| Annual | 5.9 °C | 15.4 °C | 1002.28 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 | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |