Grampian, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.4 °F (low) to 57.7 °F (high). Annual precipitation averages 48.9 Inches. Grampian is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.4 °F | 32.4 °F | 3.81 in. |
| February | 17.5 °F | 35.5 °F | 3.13 in. |
| March | 24.5 °F | 44.5 °F | 3.71 in. |
| April | 35.1 °F | 58.4 °F | 4.22 in. |
| May | 45.8 °F | 69.1 °F | 4.27 in. |
| June | 54.0 °F | 76.3 °F | 5.36 in. |
| July | 58.2 °F | 80.2 °F | 4.42 in. |
| August | 56.8 °F | 78.8 °F | 4.3 in. |
| September | 49.8 °F | 72.1 °F | 4.24 in. |
| October | 39.1 °F | 60.3 °F | 4.16 in. |
| November | 29.6 °F | 47.7 °F | 3.5 in. |
| December | 22.3 °F | 36.7 °F | 3.77 in. |
| Annual | 37.4 °F | 57.7 °F | 48.89 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |