Reardan, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 1.9 °C (low) to 13.8 °C (high). Annual precipitation averages 448.6 Millimeters. Reardan 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. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.4 °C | 0.6 °C | 55.88 mm |
| February | -4.6 °C | 3.5 °C | 37.85 mm |
| March | -1.9 °C | 8.6 °C | 48.01 mm |
| April | 0.7 °C | 13.2 °C | 33.78 mm |
| May | 4.8 °C | 18.6 °C | 40.89 mm |
| June | 7.9 °C | 22.2 °C | 34.54 mm |
| July | 11 °C | 28.2 °C | 12.19 mm |
| August | 10.7 °C | 28.2 °C | 11.68 mm |
| September | 6.3 °C | 22.7 °C | 14.73 mm |
| October | 1.1 °C | 14.1 °C | 37.34 mm |
| November | -2.6 °C | 5.5 °C | 55.63 mm |
| December | -5.7 °C | 0.3 °C | 66.04 mm |
| Annual | 1.9 °C | 13.8 °C | 448.56 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 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 |