Randallstown, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.3 °C (low) to 18.7 °C (high). Annual precipitation averages 1193.3 Millimeters. Randallstown is located in USDA Plant Hardiness Zone 7a. 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 | -4.2 °C | 5.5 °C | 88.65 mm |
| February | -3.2 °C | 7.2 °C | 72.39 mm |
| March | 0.5 °C | 12 °C | 106.43 mm |
| April | 6.1 °C | 18.9 °C | 95.5 mm |
| May | 11.3 °C | 24 °C | 112.01 mm |
| June | 16.4 °C | 28.7 °C | 104.65 mm |
| July | 19 °C | 31 °C | 112.52 mm |
| August | 18 °C | 29.8 °C | 85.6 mm |
| September | 14.3 °C | 26.1 °C | 124.46 mm |
| October | 7.8 °C | 19.6 °C | 108.2 mm |
| November | 2.6 °C | 13.3 °C | 83.82 mm |
| December | -1.4 °C | 7.7 °C | 99.06 mm |
| Annual | 7.3 °C | 18.7 °C | 1193.29 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 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |