Hillandale, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8 °C (low) to 19 °C (high). Annual precipitation averages 1161 Millimeters. Hillandale is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.3 °C | 6.2 °C | 78.99 mm |
| February | -2.4 °C | 7.9 °C | 69.34 mm |
| March | 1.2 °C | 12.7 °C | 101.09 mm |
| April | 6.7 °C | 19.3 °C | 88.14 mm |
| May | 12.2 °C | 23.9 °C | 113.28 mm |
| June | 17.2 °C | 28.6 °C | 117.09 mm |
| July | 19.8 °C | 30.9 °C | 112.78 mm |
| August | 18.9 °C | 29.9 °C | 94.49 mm |
| September | 15.3 °C | 26.2 °C | 114.05 mm |
| October | 8.7 °C | 19.9 °C | 97.54 mm |
| November | 2.8 °C | 13.8 °C | 79.76 mm |
| December | -0.9 °C | 8.4 °C | 94.49 mm |
| Annual | 8 °C | 19 °C | 1161.04 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Cfa - Humid Subtropical Climate |