| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°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: | 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 98953 - Zillah, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 23 | 27 | 33 | 38 | 45 | 51 | 56 | 56 | 47 | 37 | 30 | 24 | 39 |
| Avg Max Temp (°F) | 39 | 47 | 57 | 65 | 74 | 81 | 88 | 88 | 79 | 66 | 49 | 38 | 64 |
| Avg Precip (In.) | 1.08 | .69 | .69 | .57 | .59 | .56 | .26 | .38 | .41 | .55 | 1.04 | 1.21 | 8.03 |