Lemont, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39 °F (low) to 59.7 °F (high). Annual precipitation averages 40.7 Inches. Lemont is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.2 °F | 34.6 °F | 2.69 in. |
| February | 19.1 °F | 37.7 °F | 2.23 in. |
| March | 26.2 °F | 46.6 °F | 3.29 in. |
| April | 36.7 °F | 60.1 °F | 3.56 in. |
| May | 47.0 °F | 70.6 °F | 3.86 in. |
| June | 56.0 °F | 78.2 °F | 3.93 in. |
| July | 60.2 °F | 82.5 °F | 3.82 in. |
| August | 58.4 °F | 80.7 °F | 3.98 in. |
| September | 51.1 °F | 73.8 °F | 4.09 in. |
| October | 40.1 °F | 61.9 °F | 3.6 in. |
| November | 30.9 °F | 50.1 °F | 2.62 in. |
| December | 23.6 °F | 39.0 °F | 3.07 in. |
| Annual | 39 °F | 59.7 °F | 40.74 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |