Dayton, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 4.8 °C (low) to 16.7 °C (high). Annual precipitation averages 478.5 Millimeters. Dayton is located in USDA Plant Hardiness Zone 7a. 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 | -2.3 °C | 4.7 °C | 53.59 mm |
| February | -1.3 °C | 7.2 °C | 43.94 mm |
| March | 1.4 °C | 11.8 °C | 56.9 mm |
| April | 3.7 °C | 15.7 °C | 45.72 mm |
| May | 7.5 °C | 20.6 °C | 44.2 mm |
| June | 10.3 °C | 24.5 °C | 31.5 mm |
| July | 13.5 °C | 30.6 °C | 9.91 mm |
| August | 13.4 °C | 30.5 °C | 11.94 mm |
| September | 9.7 °C | 25.1 °C | 18.54 mm |
| October | 4.4 °C | 17 °C | 41.4 mm |
| November | 0.3 °C | 8.9 °C | 60.45 mm |
| December | -2.5 °C | 4.2 °C | 60.45 mm |
| Annual | 4.8 °C | 16.7 °C | 478.54 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |