Knox, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3 °C (low) to 14.7 °C (high). Annual precipitation averages 1188.2 Millimeters. Knox 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.3 °C | 0.7 °C | 87.88 mm |
| February | -8 °C | 2.2 °C | 63.25 mm |
| March | -4.1 °C | 7.4 °C | 86.87 mm |
| April | 1.6 °C | 14.9 °C | 101.6 mm |
| May | 7.2 °C | 21.1 °C | 99.57 mm |
| June | 12.1 °C | 25.2 °C | 133.6 mm |
| July | 14.3 °C | 27.2 °C | 129.29 mm |
| August | 13.6 °C | 26.8 °C | 107.95 mm |
| September | 9.8 °C | 22.8 °C | 106.68 mm |
| October | 4.1 °C | 16 °C | 89.66 mm |
| November | -1.2 °C | 9.1 °C | 91.44 mm |
| December | -4.9 °C | 3.1 °C | 90.42 mm |
| Annual | 3 °C | 14.7 °C | 1188.21 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |