| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°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 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. 21 - Apr. 30 |
| 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 99357 - Royal City, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 23 | 27 | 32 | 38 | 46 | 53 | 58 | 56 | 47 | 37 | 30 | 23 | 39 |
| Avg Max Temp (°F) | 38 | 46 | 57 | 66 | 75 | 82 | 90 | 89 | 80 | 66 | 48 | 38 | 64 |
| Avg Precip (In.) | 1 | .81 | .73 | .46 | .59 | .49 | .36 | .33 | .4 | .52 | 1.15 | 1.29 | 8.12 |