| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| Average First Frost Date: | Aug. 11 - Aug. 20 | |
| Average Last Frost Date: | Jun. 21 - Jun. 30 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 15y - Granitic Selkirk Mountains | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 99139 - Ione, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 22 | 27 | 33 | 41 | 47 | 51 | 50 | 43 | 35 | 27 | 21 | 35 |
| Avg Max Temp (°F) | 31 | 37 | 47 | 58 | 65 | 72 | 80 | 81 | 71 | 56 | 39 | 31 | 56 |
| Avg Precip (In.) | 2.7 | 2.1 | 1.99 | 1.72 | 2.35 | 2.69 | 1.52 | 1.15 | 1.44 | 2.56 | 2.81 | 3.27 | 26.31 |