Preston, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47.2 °F (low) to 67 °F (high). Annual precipitation averages 45 Inches. Preston 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 27.4 °F | 44.5 °F | 3.35 in. |
| February | 28.4 °F | 47.2 °F | 2.84 in. |
| March | 34.8 °F | 54.8 °F | 4.06 in. |
| April | 44.7 °F | 66.5 °F | 3.54 in. |
| May | 54.4 °F | 75.2 °F | 3.72 in. |
| June | 63.7 °F | 84.1 °F | 4.19 in. |
| July | 68.4 °F | 88.3 °F | 4.12 in. |
| August | 66.1 °F | 86.1 °F | 4.59 in. |
| September | 59.7 °F | 80.4 °F | 3.79 in. |
| October | 48.7 °F | 69.6 °F | 3.89 in. |
| November | 38.4 °F | 58.3 °F | 3.12 in. |
| December | 31.7 °F | 48.9 °F | 3.75 in. |
| Annual | 47.2 °F | 67 °F | 44.96 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 7b : 5°F to 10°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |