Jefferson, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.6 °F (low) to 64.7 °F (high). Annual precipitation averages 42.9 Inches. Jefferson 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.7 °F | 41.0 °F | 2.99 in. |
| February | 26.1 °F | 44.5 °F | 2.44 in. |
| March | 32.9 °F | 52.9 °F | 3.61 in. |
| April | 42.5 °F | 65.1 °F | 3.44 in. |
| May | 52.1 °F | 73.9 °F | 4.3 in. |
| June | 60.9 °F | 82.2 °F | 4.01 in. |
| July | 65.4 °F | 86.8 °F | 4.23 in. |
| August | 63.5 °F | 84.9 °F | 3.19 in. |
| September | 56.9 °F | 78.1 °F | 4.49 in. |
| October | 45.7 °F | 66.6 °F | 3.57 in. |
| November | 35.8 °F | 55.4 °F | 3.08 in. |
| December | 28.5 °F | 44.9 °F | 3.57 in. |
| Annual | 44.6 °F | 64.7 °F | 42.92 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |