Hazel Dell, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.5 °C (low) to 16.9 °C (high). Annual precipitation averages 1072.7 Millimeters. Hazel Dell is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.6 °C | 8.2 °C | 152.91 mm |
| February | 1.7 °C | 10.3 °C | 105.16 mm |
| March | 3.2 °C | 13.1 °C | 119.89 mm |
| April | 5 °C | 15.7 °C | 86.87 mm |
| May | 8.1 °C | 19.7 °C | 67.31 mm |
| June | 10.4 °C | 22.3 °C | 46.48 mm |
| July | 12.7 °C | 26.4 °C | 13.21 mm |
| August | 12.7 °C | 27.1 °C | 15.24 mm |
| September | 10.2 °C | 23.9 °C | 41.15 mm |
| October | 6.7 °C | 17.4 °C | 97.28 mm |
| November | 3.7 °C | 11.4 °C | 152.15 mm |
| December | 1.4 °C | 7.8 °C | 175.01 mm |
| Annual | 6.5 °C | 16.9 °C | 1072.66 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |