| 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: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | May 21 - May 31 | |
| Koppen-Geiger Climate Zone: | Dsb - Humid Continental Climate - Dry Cool Summer | |
| Ecoregion: | 15r - Okanogan-Colville Xeric Valleys and Foothills | |
| Current Drought Status: | Moderate Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 99034 - Tumtum, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 23 | 28 | 33 | 40 | 46 | 51 | 50 | 42 | 33 | 28 | 21 | 35 |
| Avg Max Temp (°F) | 33 | 39 | 48 | 58 | 67 | 74 | 84 | 84 | 74 | 59 | 41 | 33 | 58 |
| Avg Precip (In.) | 2.2 | 2.14 | 2.06 | 1.62 | 1.98 | 1.66 | 1.03 | .71 | .95 | 1.32 | 3.04 | 2.99 | 21.72 |