Leonardtown, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.9 °C (low) to 19.7 °C (high). Annual precipitation averages 1142 Millimeters. Leonardtown is located in USDA Plant Hardiness Zone 7b. 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 | -2.2 °C | 7.7 °C | 79.5 mm |
| February | -1.4 °C | 9.1 °C | 71.63 mm |
| March | 2.3 °C | 13.4 °C | 104.39 mm |
| April | 7.7 °C | 19.8 °C | 88.9 mm |
| May | 12.8 °C | 24.3 °C | 103.63 mm |
| June | 17.8 °C | 28.8 °C | 101.85 mm |
| July | 20.4 °C | 31 °C | 111 mm |
| August | 19.5 °C | 30.1 °C | 97.79 mm |
| September | 16 °C | 26.8 °C | 105.16 mm |
| October | 9.5 °C | 20.7 °C | 100.58 mm |
| November | 3.8 °C | 14.9 °C | 83.31 mm |
| December | 0.4 °C | 10 °C | 94.23 mm |
| Annual | 8.9 °C | 19.7 °C | 1141.97 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |