Monongahela, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.9 °C (low) to 17.2 °C (high). Annual precipitation averages 1046 Millimeters. Monongahela 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 | -5.4 °C | 3.7 °C | 78.99 mm |
| February | -4.8 °C | 5.1 °C | 66.29 mm |
| March | -1 °C | 10.3 °C | 84.07 mm |
| April | 4.4 °C | 17.8 °C | 85.09 mm |
| May | 10.2 °C | 22.8 °C | 103.63 mm |
| June | 15.2 °C | 27.2 °C | 112.01 mm |
| July | 17.4 °C | 29.3 °C | 106.43 mm |
| August | 16.8 °C | 28.8 °C | 91.19 mm |
| September | 12.8 °C | 25.3 °C | 87.63 mm |
| October | 6.6 °C | 18.6 °C | 75.69 mm |
| November | 1.2 °C | 11.8 °C | 76.2 mm |
| December | -2.6 °C | 6.1 °C | 78.74 mm |
| Annual | 5.9 °C | 17.2 °C | 1045.96 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |