Okanogan, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 4.2 °C (low) to 17 °C (high). Annual precipitation averages 303.5 Millimeters. Okanogan is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.7 °C | 1.2 °C | 35.31 mm |
| February | -3.4 °C | 5.1 °C | 25.91 mm |
| March | -0.1 °C | 12.2 °C | 29.72 mm |
| April | 3.4 °C | 17.9 °C | 22.1 mm |
| May | 7.6 °C | 23.4 °C | 29.46 mm |
| June | 11.2 °C | 27.1 °C | 25.4 mm |
| July | 14.6 °C | 32.3 °C | 13.72 mm |
| August | 14 °C | 32.1 °C | 7.87 mm |
| September | 9.2 °C | 26.7 °C | 10.92 mm |
| October | 3.7 °C | 17.2 °C | 22.1 mm |
| November | -0.9 °C | 7.4 °C | 36.07 mm |
| December | -4 °C | 1.7 °C | 44.96 mm |
| Annual | 4.2 °C | 17 °C | 303.54 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |