Mount Aetna, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.6 °C (low) to 18.1 °C (high). Annual precipitation averages 1066.3 Millimeters. Mount Aetna 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 | -4.6 °C | 4.8 °C | 77.98 mm |
| February | -3.8 °C | 6.8 °C | 59.94 mm |
| March | 0.1 °C | 11.5 °C | 89.41 mm |
| April | 5.5 °C | 18.3 °C | 92.96 mm |
| May | 10.9 °C | 23.3 °C | 107.44 mm |
| June | 15.8 °C | 28.1 °C | 95.25 mm |
| July | 18.2 °C | 30.6 °C | 96.27 mm |
| August | 17.3 °C | 29.6 °C | 89.15 mm |
| September | 13.4 °C | 25.8 °C | 104.65 mm |
| October | 7.3 °C | 19.3 °C | 91.69 mm |
| November | 1.6 °C | 12.8 °C | 76.45 mm |
| December | -2.3 °C | 6.8 °C | 85.09 mm |
| Annual | 6.6 °C | 18.1 °C | 1066.28 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 |