| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°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. 21 - Oct. 31 |
| 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: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 97882 - Umatilla, OR | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 27 | 30 | 35 | 40 | 47 | 54 | 59 | 59 | 50 | 41 | 34 | 29 | 42 |
| Avg Max Temp (°F) | 40 | 47 | 57 | 65 | 73 | 80 | 88 | 87 | 78 | 65 | 50 | 41 | 64 |
| Avg Precip (In.) | 1.18 | .93 | .86 | .66 | .83 | .69 | .27 | .33 | .41 | .79 | 1.38 | 1.25 | 9.58 |