South Cle Elum, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2.2 °C (low) to 13.9 °C (high). Annual precipitation averages 620.5 Millimeters. South Cle Elum is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.8 °C | 1.7 °C | 96.27 mm |
| February | -4.2 °C | 4.8 °C | 67.06 mm |
| March | -2.1 °C | 8.9 °C | 55.37 mm |
| April | 0.8 °C | 13.2 °C | 34.04 mm |
| May | 4.8 °C | 18.2 °C | 31.5 mm |
| June | 8.3 °C | 21.4 °C | 23.62 mm |
| July | 11.3 °C | 26.6 °C | 11.43 mm |
| August | 10.9 °C | 27 °C | 8.64 mm |
| September | 6.6 °C | 22.4 °C | 19.81 mm |
| October | 1.8 °C | 14.5 °C | 56.64 mm |
| November | -2.1 °C | 6.3 °C | 99.57 mm |
| December | -4.9 °C | 1.5 °C | 116.59 mm |
| Annual | 2.2 °C | 13.9 °C | 620.54 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |