Loon Lake, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 1.2 °C (low) to 14.3 °C (high). Annual precipitation averages 643.6 Millimeters. Loon Lake is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.1 °C | 1.1 °C | 79.76 mm |
| February | -5.5 °C | 4.2 °C | 53.59 mm |
| March | -2.7 °C | 9 °C | 72.14 mm |
| April | -0.1 °C | 13.7 °C | 45.72 mm |
| May | 4.1 °C | 19.2 °C | 54.86 mm |
| June | 7.2 °C | 22.6 °C | 50.55 mm |
| July | 10 °C | 28.7 °C | 16.51 mm |
| August | 9.6 °C | 28.9 °C | 12.7 mm |
| September | 5.6 °C | 23.3 °C | 20.32 mm |
| October | 0.7 °C | 14.3 °C | 50.8 mm |
| November | -2.7 °C | 5.7 °C | 78.99 mm |
| December | -5.9 °C | 0.7 °C | 107.7 mm |
| Annual | 1.2 °C | 14.3 °C | 643.64 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |