Seneca, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.1 °F (low) to 57.8 °F (high). Annual precipitation averages 46.9 Inches. Seneca is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.1 °F | 32.6 °F | 3.29 in. |
| February | 17.8 °F | 35.4 °F | 2.41 in. |
| March | 24.8 °F | 44.4 °F | 3.57 in. |
| April | 35.7 °F | 57.8 °F | 4.06 in. |
| May | 46.1 °F | 69.1 °F | 4.06 in. |
| June | 54.7 °F | 76.7 °F | 5.37 in. |
| July | 58.7 °F | 80.7 °F | 5.1 in. |
| August | 57.3 °F | 79.3 °F | 4.26 in. |
| September | 50.8 °F | 72.6 °F | 4.17 in. |
| October | 40.3 °F | 60.4 °F | 3.6 in. |
| November | 30.9 °F | 48.1 °F | 3.46 in. |
| December | 23.4 °F | 37.0 °F | 3.55 in. |
| Annual | 38.1 °F | 57.8 °F | 46.9 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |