| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 6b: -5F to 0F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | 10i - Deep Loess Foothills |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 99328 - Dayton, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 26 | 29 | 34 | 38 | 44 | 50 | 55 | 55 | 47 | 38 | 33 | 27 | 40 |
| Avg Max Temp (°F) | 40 | 46 | 53 | 61 | 69 | 77 | 86 | 87 | 77 | 64 | 48 | 40 | 62 |
| Avg Precip (In.) | 2.24 | 1.82 | 1.99 | 1.65 | 1.59 | 1.17 | .54 | .73 | .87 | 1.48 | 2.59 | 2.45 | 19.11 |