Jamestown, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39 °F (low) to 59.4 °F (high). Annual precipitation averages 44.1 Inches. Jamestown 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 | 18.0 °F | 34.0 °F | 3.18 in. |
| February | 18.2 °F | 36.5 °F | 2.28 in. |
| March | 25.8 °F | 45.6 °F | 3.02 in. |
| April | 36.1 °F | 59.3 °F | 4.01 in. |
| May | 46.8 °F | 70.4 °F | 4.0 in. |
| June | 55.7 °F | 78.4 °F | 4.81 in. |
| July | 59.8 °F | 82.1 °F | 4.61 in. |
| August | 58.0 °F | 80.6 °F | 3.9 in. |
| September | 51.5 °F | 74.5 °F | 4.26 in. |
| October | 41.1 °F | 62.4 °F | 3.63 in. |
| November | 32.5 °F | 49.7 °F | 3.22 in. |
| December | 24.4 °F | 38.9 °F | 3.22 in. |
| Annual | 39 °F | 59.4 °F | 44.14 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 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |