Glassmanor, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 48.9 °F (low) to 66.9 °F (high). Annual precipitation averages 45.2 Inches. Glassmanor is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 28.3 °F | 44.1 °F | 3.07 in. |
| February | 29.7 °F | 47.4 °F | 2.66 in. |
| March | 36.6 °F | 55.5 °F | 3.84 in. |
| April | 46.7 °F | 67.0 °F | 3.43 in. |
| May | 56.3 °F | 75.3 °F | 4.45 in. |
| June | 65.6 °F | 84.0 °F | 4.57 in. |
| July | 70.4 °F | 88.5 °F | 4.65 in. |
| August | 68.6 °F | 86.7 °F | 3.66 in. |
| September | 62.0 °F | 80.0 °F | 4.25 in. |
| October | 50.2 °F | 68.6 °F | 3.82 in. |
| November | 39.8 °F | 57.5 °F | 3.04 in. |
| December | 32.6 °F | 48.2 °F | 3.72 in. |
| Annual | 48.9 °F | 66.9 °F | 45.16 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |