| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | BSk - Cold Semi-Arid Climate |
| Ecoregion: | 10e - Pleistocene Lake Basins |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 98823 - Ephrata, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 27 | 33 | 38 | 47 | 54 | 60 | 59 | 50 | 39 | 30 | 22 | 40 |
| Avg Max Temp (°F) | 34 | 42 | 53 | 63 | 72 | 80 | 88 | 87 | 78 | 63 | 45 | 34 | 62 |
| Avg Precip (In.) | .84 | .78 | .75 | .48 | .68 | .56 | .44 | .26 | .38 | .48 | 1.05 | 1.21 | 7.9 |