Ellicott City, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.8 °C (low) to 19 °C (high). Annual precipitation averages 1221.7 Millimeters. Ellicott City 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 | -3.4 °C | 6.2 °C | 85.6 mm |
| February | -2.7 °C | 7.8 °C | 76.2 mm |
| March | 1.1 °C | 12.4 °C | 109.22 mm |
| April | 6.6 °C | 19.1 °C | 94.49 mm |
| May | 12 °C | 24.1 °C | 114.3 mm |
| June | 17.1 °C | 28.8 °C | 113.79 mm |
| July | 19.7 °C | 31.2 °C | 115.57 mm |
| August | 18.7 °C | 30.1 °C | 100.08 mm |
| September | 14.9 °C | 26.4 °C | 120.9 mm |
| October | 8.3 °C | 20.1 °C | 105.66 mm |
| November | 2.9 °C | 13.8 °C | 85.34 mm |
| December | -1.1 °C | 8.4 °C | 100.58 mm |
| Annual | 7.8 °C | 19 °C | 1221.73 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |