Lemont Furnace, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 16.9 °C (high). Annual precipitation averages 1153.7 Millimeters. Lemont Furnace is located in USDA Plant Hardiness Zone 6b. 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 | -6.2 °C | 3.5 °C | 86.61 mm |
| February | -5.6 °C | 5.2 °C | 73.66 mm |
| March | -1.8 °C | 10.3 °C | 95.76 mm |
| April | 3.6 °C | 17.4 °C | 97.28 mm |
| May | 9.3 °C | 22.7 °C | 113.79 mm |
| June | 14.2 °C | 26.8 °C | 123.95 mm |
| July | 16.5 °C | 28.7 °C | 120.4 mm |
| August | 15.8 °C | 28.3 °C | 97.54 mm |
| September | 11.7 °C | 24.8 °C | 91.69 mm |
| October | 5.4 °C | 18.2 °C | 81.53 mm |
| November | 0.1 °C | 11.4 °C | 84.07 mm |
| December | -3.4 °C | 5.8 °C | 87.38 mm |
| Annual | 5 °C | 16.9 °C | 1153.66 mm |
| 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 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 |