| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F |
| 2012 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 7a: 0F to 5F |
| Average First Frost Date: | Oct. 21 - Oct. 31 |
| Average Last Frost Date: | Apr. 11 - Apr. 20 |
| Koppen-Geiger Climate Zone: | BWk - Cold Desert Climate |
| Ecoregion: | 10e - Pleistocene Lake Basins |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 99353 - West Richland, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 26 | 30 | 35 | 40 | 47 | 53 | 58 | 58 | 50 | 40 | 33 | 27 | 41 |
| Avg Max Temp (°F) | 40 | 47 | 57 | 65 | 73 | 81 | 88 | 88 | 79 | 65 | 49 | 40 | 64 |
| Avg Precip (In.) | 1.03 | .78 | .74 | .58 | .66 | .46 | .25 | .33 | .38 | .57 | 1.1 | 1.13 | 8.01 |