Knoxville, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.8 °C (low) to 14.4 °C (high). Annual precipitation averages 942.6 Millimeters. Knoxville is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 0.2 °C | 58.17 mm |
| February | -9.5 °C | 1.7 °C | 45.97 mm |
| March | -5.7 °C | 6.3 °C | 66.8 mm |
| April | 0.1 °C | 13.9 °C | 77.47 mm |
| May | 6.1 °C | 20.7 °C | 86.36 mm |
| June | 11.2 °C | 25.3 °C | 99.31 mm |
| July | 13.4 °C | 27.5 °C | 95 mm |
| August | 12.7 °C | 26.8 °C | 91.44 mm |
| September | 8.9 °C | 22.9 °C | 97.03 mm |
| October | 3.1 °C | 16 °C | 91.69 mm |
| November | -1.9 °C | 8.6 °C | 69.85 mm |
| December | -6.2 °C | 2.8 °C | 63.5 mm |
| Annual | 1.8 °C | 14.4 °C | 942.59 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |