| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°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 |
| 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: | 12a - Treasure Valley |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 97914 - Ontario, OR | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 25 | 31 | 37 | 45 | 52 | 58 | 55 | 46 | 35 | 28 | 21 | 38 |
| Avg Max Temp (°F) | 35 | 44 | 56 | 65 | 75 | 83 | 92 | 91 | 81 | 67 | 48 | 37 | 64 |
| Avg Precip (In.) | 1.3 | .9 | .86 | .69 | .94 | .63 | .3 | .29 | .48 | .56 | 1.21 | 1.4 | 9.56 |