Mercersville, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.5 °F (low) to 65.5 °F (high). Annual precipitation averages 41.8 Inches. 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 | 22.1 °F | 41.4 °F | 2.95 in. |
| February | 23.6 °F | 45.1 °F | 2.37 in. |
| March | 30.0 °F | 53.7 °F | 3.51 in. |
| April | 40.8 °F | 66.0 °F | 3.5 in. |
| May | 50.8 °F | 74.7 °F | 4.27 in. |
| June | 59.3 °F | 83.3 °F | 3.93 in. |
| July | 63.9 °F | 87.7 °F | 3.84 in. |
| August | 62.3 °F | 86.1 °F | 3.41 in. |
| September | 55.1 °F | 79.4 °F | 4.2 in. |
| October | 42.5 °F | 67.7 °F | 3.45 in. |
| November | 33.1 °F | 55.8 °F | 2.99 in. |
| December | 26.6 °F | 45.0 °F | 3.33 in. |
| Annual | 42.5 °F | 65.5 °F | 41.75 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |