Fairmount, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.1 °C (low) to 19.6 °C (high). Annual precipitation averages 1149.9 Millimeters. Fairmount is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.2 °C | 7.9 °C | 82.55 mm |
| February | -0.6 °C | 9.2 °C | 74.42 mm |
| March | 2.9 °C | 13 °C | 104.14 mm |
| April | 8.4 °C | 19.1 °C | 86.61 mm |
| May | 13.8 °C | 23.8 °C | 90.42 mm |
| June | 19.1 °C | 28.3 °C | 100.84 mm |
| July | 21.8 °C | 30.8 °C | 111 mm |
| August | 20.9 °C | 29.8 °C | 120.9 mm |
| September | 17.7 °C | 26.8 °C | 108.97 mm |
| October | 11.4 °C | 21.2 °C | 101.6 mm |
| November | 5.4 °C | 15.1 °C | 77.47 mm |
| December | 1.4 °C | 10.4 °C | 90.93 mm |
| Annual | 10.1 °C | 19.6 °C | 1149.85 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |