Deer Park, Maryland has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.1 °F (low) to 58.1 °F (high). Annual precipitation averages 53 Inches. Deer Park is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.5 °F | 34.8 °F | 4.43 in. |
| February | 19.3 °F | 38.3 °F | 4.21 in. |
| March | 25.3 °F | 46.3 °F | 4.69 in. |
| April | 35.0 °F | 59.2 °F | 4.66 in. |
| May | 45.1 °F | 67.7 °F | 5.29 in. |
| June | 53.5 °F | 74.8 °F | 5.14 in. |
| July | 57.2 °F | 78.5 °F | 5.03 in. |
| August | 55.6 °F | 77.2 °F | 4.19 in. |
| September | 48.5 °F | 71.6 °F | 3.92 in. |
| October | 37.7 °F | 60.6 °F | 3.49 in. |
| November | 28.6 °F | 48.8 °F | 3.6 in. |
| December | 22.2 °F | 39.1 °F | 4.36 in. |
| Annual | 37.1 °F | 58.1 °F | 53.01 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |