Severn, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 45.9 °F (low) to 66.2 °F (high). Annual precipitation averages 47.1 Inches. Severn 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.4 °F | 43.2 °F | 3.25 in. |
| February | 26.9 °F | 46.1 °F | 2.97 in. |
| March | 33.7 °F | 54.4 °F | 4.28 in. |
| April | 43.6 °F | 66.3 °F | 3.57 in. |
| May | 53.4 °F | 75.0 °F | 4.34 in. |
| June | 62.6 °F | 83.5 °F | 4.37 in. |
| July | 67.4 °F | 87.9 °F | 4.56 in. |
| August | 65.5 °F | 86.1 °F | 3.99 in. |
| September | 58.8 °F | 79.5 °F | 4.59 in. |
| October | 46.7 °F | 68.1 °F | 3.99 in. |
| November | 36.6 °F | 57.0 °F | 3.24 in. |
| December | 29.6 °F | 47.3 °F | 3.99 in. |
| Annual | 45.9 °F | 66.2 °F | 47.14 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |