National, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.1 °F (low) to 60.2 °F (high). Annual precipitation averages 44.1 Inches. National is located in USDA Plant Hardiness Zone 6b. 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 | 20.2 °F | 35.5 °F | 3.1 in. |
| February | 21.3 °F | 38.9 °F | 2.93 in. |
| March | 27.9 °F | 47.6 °F | 3.94 in. |
| April | 37.9 °F | 61.9 °F | 4.01 in. |
| May | 47.9 °F | 70.5 °F | 4.8 in. |
| June | 56.3 °F | 78.1 °F | 4.57 in. |
| July | 60.4 °F | 82.1 °F | 3.76 in. |
| August | 58.8 °F | 80.8 °F | 3.42 in. |
| September | 52.2 °F | 74.5 °F | 3.91 in. |
| October | 41.5 °F | 62.9 °F | 3.28 in. |
| November | 32.0 °F | 50.0 °F | 3.02 in. |
| December | 24.9 °F | 39.7 °F | 3.38 in. |
| Annual | 40.1 °F | 60.2 °F | 44.12 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |