Monessen, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 16.6 °C (high). Annual precipitation averages 1052.1 Millimeters. Monessen 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 | -6.1 °C | 3.2 °C | 78.49 mm |
| February | -5.4 °C | 4.6 °C | 68.07 mm |
| March | -1.5 °C | 9.8 °C | 85.85 mm |
| April | 3.9 °C | 17 °C | 85.85 mm |
| May | 9.7 °C | 22.2 °C | 104.65 mm |
| June | 14.6 °C | 26.6 °C | 112.27 mm |
| July | 16.9 °C | 28.7 °C | 105.16 mm |
| August | 16.1 °C | 28.2 °C | 92.46 mm |
| September | 12.2 °C | 24.7 °C | 86.87 mm |
| October | 5.9 °C | 17.9 °C | 75.69 mm |
| November | 0.7 °C | 11.3 °C | 77.22 mm |
| December | -3.2 °C | 5.5 °C | 79.5 mm |
| Annual | 5.3 °C | 16.6 °C | 1052.08 mm |
| 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 : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |