Curlew, Washington has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.2 °C (low) to 14.6 °C (high). Annual precipitation averages 480.3 Millimeters. Curlew 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 | -6.8 °C | -0.7 °C | 50.04 mm |
| February | -5.9 °C | 3.4 °C | 33.53 mm |
| March | -2.7 °C | 9.8 °C | 37.59 mm |
| April | 0.2 °C | 15.6 °C | 37.34 mm |
| May | 4.7 °C | 21.1 °C | 57.15 mm |
| June | 8.1 °C | 23.9 °C | 60.71 mm |
| July | 10.3 °C | 29.3 °C | 29.97 mm |
| August | 9.8 °C | 29.6 °C | 17.78 mm |
| September | 5.8 °C | 24.1 °C | 22.35 mm |
| October | 0.9 °C | 14.4 °C | 33.53 mm |
| November | -3.1 °C | 5 °C | 46.48 mm |
| December | -6.6 °C | -0.3 °C | 53.85 mm |
| Annual | 1.2 °C | 14.6 °C | 480.32 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |