Allen, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.9 °F (low) to 68.1 °F (high). Annual precipitation averages 46.4 Inches. Allen is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 27.7 °F | 46.6 °F | 3.43 in. |
| February | 28.5 °F | 49.0 °F | 2.96 in. |
| March | 34.9 °F | 56.2 °F | 4.09 in. |
| April | 44.3 °F | 67.7 °F | 3.53 in. |
| May | 53.6 °F | 75.9 °F | 3.61 in. |
| June | 62.9 °F | 84.1 °F | 4.04 in. |
| July | 68.0 °F | 88.5 °F | 4.41 in. |
| August | 65.7 °F | 86.3 °F | 5.01 in. |
| September | 59.7 °F | 81.1 °F | 4.44 in. |
| October | 48.1 °F | 70.8 °F | 4.04 in. |
| November | 38.0 °F | 59.8 °F | 3.18 in. |
| December | 31.5 °F | 50.8 °F | 3.7 in. |
| Annual | 46.9 °F | 68.1 °F | 46.44 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |