| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 6b: -5F to 0F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 11 - Apr. 20 |
| Koppen-Geiger Climate Zone: | BSk - Cold Semi-Arid Climate |
| Ecoregion: | 10e - Pleistocene Lake Basins |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 97838 - Hermiston, OR | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 26 | 29 | 34 | 40 | 46 | 53 | 58 | 57 | 48 | 38 | 33 | 27 | 41 |
| Avg Max Temp (°F) | 41 | 48 | 58 | 65 | 73 | 81 | 89 | 88 | 79 | 66 | 51 | 42 | 65 |
| Avg Precip (In.) | 1.49 | 1.06 | .94 | .86 | .86 | .52 | .23 | .35 | .47 | .68 | 1.5 | 1.33 | 10.29 |