Marydel, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.5 °C (low) to 18.6 °C (high). Annual precipitation averages 1183.6 Millimeters. Marydel 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 | -3.8 °C | 6.2 °C | 86.87 mm |
| February | -3.3 °C | 7.3 °C | 77.72 mm |
| March | 0.8 °C | 11.7 °C | 104.39 mm |
| April | 6.4 °C | 18.1 °C | 91.44 mm |
| May | 11.7 °C | 23.1 °C | 101.09 mm |
| June | 16.7 °C | 27.9 °C | 113.79 mm |
| July | 19.5 °C | 30.4 °C | 109.73 mm |
| August | 18.4 °C | 29.4 °C | 111 mm |
| September | 14.7 °C | 26.3 °C | 106.43 mm |
| October | 7.9 °C | 20 °C | 100.58 mm |
| November | 2.3 °C | 14 °C | 81.28 mm |
| December | -1.3 °C | 8.7 °C | 99.31 mm |
| Annual | 7.5 °C | 18.6 °C | 1183.63 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 7a : -17.8°C to -15°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |