Plains, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 40 °F (low) to 60.8 °F (high). Annual precipitation averages 42.6 Inches. Plains is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.6 °F | 35.5 °F | 2.61 in. |
| February | 19.7 °F | 38.4 °F | 2.4 in. |
| March | 27.1 °F | 47.0 °F | 2.69 in. |
| April | 37.6 °F | 60.2 °F | 3.59 in. |
| May | 48.0 °F | 71.6 °F | 3.57 in. |
| June | 56.9 °F | 79.6 °F | 4.59 in. |
| July | 61.4 °F | 84.5 °F | 4.38 in. |
| August | 59.7 °F | 82.4 °F | 3.85 in. |
| September | 52.5 °F | 75.5 °F | 4.63 in. |
| October | 41.6 °F | 62.9 °F | 4.26 in. |
| November | 32.6 °F | 51.3 °F | 2.88 in. |
| December | 24.7 °F | 40.5 °F | 3.11 in. |
| Annual | 40 °F | 60.8 °F | 42.56 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 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 |