Seneca, Oregon has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 26.4 °F (low) to 57.2 °F (high). Annual precipitation averages 13.9 Inches. Seneca is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 21 - Jun. 30 through the first frost around July 11 - July 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.3 °F | 36.0 °F | 1.54 in. |
| February | 16.2 °F | 40.4 °F | 1.05 in. |
| March | 21.7 °F | 46.5 °F | 1.31 in. |
| April | 26.3 °F | 52.7 °F | 1.15 in. |
| May | 32.6 °F | 61.9 °F | 1.8 in. |
| June | 37.1 °F | 70.4 °F | 1.18 in. |
| July | 41.0 °F | 82.8 °F | 0.46 in. |
| August | 38.3 °F | 82.6 °F | 0.42 in. |
| September | 31.7 °F | 73.8 °F | 0.65 in. |
| October | 24.2 °F | 59.0 °F | 1.13 in. |
| November | 19.7 °F | 44.3 °F | 1.44 in. |
| December | 13.5 °F | 35.6 °F | 1.73 in. |
| Annual | 26.4 °F | 57.2 °F | 13.86 in. |
| Average First Frost Date | July 11 - July 20 |
| Average Last Frost Date | Jun. 21 - Jun. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |