Sunnyslope, Washington has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 4.7 °C (low) to 17 °C (high). Annual precipitation averages 248.4 Millimeters. Sunnyslope is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4 °C | 2.2 °C | 37.59 mm |
| February | -2.7 °C | 6.4 °C | 26.16 mm |
| March | 0.3 °C | 12.1 °C | 22.1 mm |
| April | 3.8 °C | 17.5 °C | 16.26 mm |
| May | 8.1 °C | 22.7 °C | 19.81 mm |
| June | 11.7 °C | 26.3 °C | 16.26 mm |
| July | 15.1 °C | 31.6 °C | 7.62 mm |
| August | 14.7 °C | 31.2 °C | 4.57 mm |
| September | 10.1 °C | 26.1 °C | 7.37 mm |
| October | 4.2 °C | 17.3 °C | 19.3 mm |
| November | -0.6 °C | 8.1 °C | 29.46 mm |
| December | -3.8 °C | 2.1 °C | 41.91 mm |
| Annual | 4.7 °C | 17 °C | 248.41 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |