Tunnelhill, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.3 °C (low) to 13.6 °C (high). Annual precipitation averages 1238 Millimeters. Tunnelhill is located in USDA Plant Hardiness Zone 6b. 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 | -7.4 °C | 0 °C | 84.84 mm |
| February | -6.9 °C | 1.4 °C | 73.66 mm |
| March | -3.1 °C | 6.1 °C | 102.11 mm |
| April | 3.2 °C | 14 °C | 112.52 mm |
| May | 9.1 °C | 19.3 °C | 113.03 mm |
| June | 13.6 °C | 23.7 °C | 120.65 mm |
| July | 16 °C | 25.8 °C | 118.11 mm |
| August | 14.9 °C | 25 °C | 108.71 mm |
| September | 11.4 °C | 21.6 °C | 114.05 mm |
| October | 5.6 °C | 15.2 °C | 99.57 mm |
| November | -0.1 °C | 8.3 °C | 91.95 mm |
| December | -4.4 °C | 2.4 °C | 98.81 mm |
| Annual | 4.3 °C | 13.6 °C | 1238.01 mm |
| 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |