| 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 1b: -15F to -10F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Dsb - Humid Continental Climate - Dry Cool Summer |
| Ecoregion: | 15s - Spokane Valley Outwash Plains |
| Heat Zone Days: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 99026 - Nine Mile Falls, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 25 | 28 | 34 | 41 | 47 | 51 | 52 | 43 | 34 | 29 | 23 | 36 |
| Avg Max Temp (°F) | 34 | 41 | 49 | 59 | 68 | 75 | 84 | 85 | 74 | 60 | 43 | 35 | 59 |
| Avg Precip (In.) | 1.63 | 1.63 | 1.61 | 1.15 | 1.51 | 1.24 | .9 | .53 | .81 | 1.01 | 2.24 | 1.75 | 16.04 |