Henderson, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.4 °C (low) to 18.6 °C (high). Annual precipitation averages 1195.3 Millimeters. Henderson 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 | -3.9 °C | 6.2 °C | 89.41 mm |
| February | -3.3 °C | 7.4 °C | 81.03 mm |
| March | 0.7 °C | 11.7 °C | 103.63 mm |
| April | 6.3 °C | 18.2 °C | 92.46 mm |
| May | 11.7 °C | 23.1 °C | 102.62 mm |
| June | 16.7 °C | 27.9 °C | 114.05 mm |
| July | 19.4 °C | 30.4 °C | 110.24 mm |
| August | 18.3 °C | 29.5 °C | 110.74 mm |
| September | 14.6 °C | 26.3 °C | 105.66 mm |
| October | 7.8 °C | 20.1 °C | 101.6 mm |
| November | 2.2 °C | 14 °C | 83.06 mm |
| December | -1.3 °C | 8.7 °C | 100.84 mm |
| Annual | 7.4 °C | 18.6 °C | 1195.34 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 |