Lemont Furnace, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.9 °F (low) to 62.5 °F (high). Annual precipitation averages 45.4 Inches. 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 | 20.8 °F | 38.3 °F | 3.41 in. |
| February | 22.0 °F | 41.3 °F | 2.9 in. |
| March | 28.7 °F | 50.5 °F | 3.77 in. |
| April | 38.4 °F | 63.4 °F | 3.83 in. |
| May | 48.8 °F | 72.8 °F | 4.48 in. |
| June | 57.5 °F | 80.2 °F | 4.88 in. |
| July | 61.7 °F | 83.7 °F | 4.74 in. |
| August | 60.4 °F | 82.9 °F | 3.84 in. |
| September | 53.1 °F | 76.6 °F | 3.61 in. |
| October | 41.8 °F | 64.8 °F | 3.21 in. |
| November | 32.1 °F | 52.6 °F | 3.31 in. |
| December | 25.8 °F | 42.4 °F | 3.44 in. |
| Annual | 40.9 °F | 62.5 °F | 45.42 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 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |