Mercersville, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.8 °C (low) to 18.6 °C (high). Annual precipitation averages 1060.5 Millimeters. Mercersville is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.5 °C | 5.2 °C | 74.93 mm |
| February | -4.7 °C | 7.3 °C | 60.2 mm |
| March | -1.1 °C | 12.1 °C | 89.15 mm |
| April | 4.9 °C | 18.9 °C | 88.9 mm |
| May | 10.4 °C | 23.7 °C | 108.46 mm |
| June | 15.2 °C | 28.5 °C | 99.82 mm |
| July | 17.7 °C | 30.9 °C | 97.54 mm |
| August | 16.8 °C | 30.1 °C | 86.61 mm |
| September | 12.8 °C | 26.3 °C | 106.68 mm |
| October | 5.8 °C | 19.8 °C | 87.63 mm |
| November | 0.6 °C | 13.2 °C | 75.95 mm |
| December | -3 °C | 7.2 °C | 84.58 mm |
| Annual | 5.8 °C | 18.6 °C | 1060.45 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |