Stillwater, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 40.2 °F (low) to 60.9 °F (high). Annual precipitation averages 46.1 Inches. Stillwater is located in USDA Plant Hardiness Zone 6b. 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 | 18.8 °F | 35.7 °F | 3.26 in. |
| February | 20.2 °F | 38.5 °F | 2.44 in. |
| March | 27.5 °F | 47.2 °F | 3.25 in. |
| April | 37.8 °F | 60.9 °F | 3.94 in. |
| May | 48.1 °F | 71.8 °F | 4.15 in. |
| June | 57.1 °F | 79.5 °F | 4.6 in. |
| July | 61.4 °F | 84.0 °F | 4.65 in. |
| August | 59.9 °F | 82.3 °F | 4.36 in. |
| September | 52.7 °F | 75.5 °F | 4.79 in. |
| October | 41.5 °F | 63.4 °F | 4.03 in. |
| November | 32.4 °F | 51.2 °F | 3.17 in. |
| December | 24.9 °F | 40.5 °F | 3.48 in. |
| Annual | 40.2 °F | 60.9 °F | 46.12 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 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |