Sisters, Oregon has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 0.1 °C (low) to 16.3 °C (high). Annual precipitation averages 355.6 Millimeters. 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 | -4.8 °C | 5.7 °C | 58.67 mm |
| February | -4.6 °C | 7.7 °C | 42.16 mm |
| March | -3 °C | 11 °C | 28.45 mm |
| April | -1.4 °C | 14.1 °C | 23.62 mm |
| May | 1.9 °C | 19.2 °C | 25.91 mm |
| June | 4.4 °C | 23.3 °C | 17.78 mm |
| July | 7.1 °C | 29.6 °C | 7.11 mm |
| August | 6.8 °C | 29.3 °C | 7.62 mm |
| September | 3.4 °C | 24.8 °C | 11.18 mm |
| October | -0.4 °C | 17.1 °C | 22.61 mm |
| November | -3 °C | 9.4 °C | 43.94 mm |
| December | -5.6 °C | 4.9 °C | 66.55 mm |
| Annual | 0.1 °C | 16.3 °C | 355.6 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |