Chewelah, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 1.5 °C (low) to 15.6 °C (high). Annual precipitation averages 537.2 Millimeters. Chewelah 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 | -5.4 °C | 1.1 °C | 67.56 mm |
| February | -5.2 °C | 5 °C | 46.48 mm |
| March | -2.1 °C | 10.5 °C | 56.64 mm |
| April | 0.6 °C | 15.8 °C | 39.88 mm |
| May | 4.8 °C | 21.3 °C | 49.28 mm |
| June | 7.7 °C | 24.6 °C | 46.48 mm |
| July | 10 °C | 30.4 °C | 20.57 mm |
| August | 9.2 °C | 30.7 °C | 13.46 mm |
| September | 5.3 °C | 24.8 °C | 17.78 mm |
| October | 0.7 °C | 15.7 °C | 41.4 mm |
| November | -2.2 °C | 6.3 °C | 65.28 mm |
| December | -5.8 °C | 1 °C | 72.39 mm |
| Annual | 1.5 °C | 15.6 °C | 537.2 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 |