Barnesville, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.4 °C (low) to 18 °C (high). Annual precipitation averages 1125.8 Millimeters. Barnesville is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.9 °C | 5 °C | 73.91 mm |
| February | -2.9 °C | 6.8 °C | 67.82 mm |
| March | 0.7 °C | 11.6 °C | 97.79 mm |
| April | 6.2 °C | 18.3 °C | 84.33 mm |
| May | 11.7 °C | 23.1 °C | 114.05 mm |
| June | 16.4 °C | 27.8 °C | 114.81 mm |
| July | 19.1 °C | 30.2 °C | 104.14 mm |
| August | 18.1 °C | 29.2 °C | 83.57 mm |
| September | 14.4 °C | 25.4 °C | 115.32 mm |
| October | 7.9 °C | 19.1 °C | 99.06 mm |
| November | 2.6 °C | 12.8 °C | 81.03 mm |
| December | -1.5 °C | 7.2 °C | 89.92 mm |
| Annual | 7.4 °C | 18 °C | 1125.75 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |