Sisters, Oregon has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 32.1 °F (low) to 61.4 °F (high). Annual precipitation averages 14 Inches. Sisters is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Aug. 1 - Aug. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.3 °F | 42.3 °F | 2.31 in. |
| February | 23.8 °F | 45.9 °F | 1.66 in. |
| March | 26.6 °F | 51.8 °F | 1.12 in. |
| April | 29.4 °F | 57.4 °F | 0.93 in. |
| May | 35.4 °F | 66.5 °F | 1.02 in. |
| June | 39.9 °F | 74.0 °F | 0.7 in. |
| July | 44.8 °F | 85.2 °F | 0.28 in. |
| August | 44.3 °F | 84.8 °F | 0.3 in. |
| September | 38.1 °F | 76.6 °F | 0.44 in. |
| October | 31.3 °F | 62.7 °F | 0.89 in. |
| November | 26.6 °F | 48.9 °F | 1.73 in. |
| December | 21.9 °F | 40.8 °F | 2.62 in. |
| Annual | 32.1 °F | 61.4 °F | 14 in. |
| Average First Frost Date | Aug. 1 - Aug. 10 |
| Average Last Frost Date | Jun. 11 - Jun. 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |