Rosemont, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44 °F (low) to 65.2 °F (high). Annual precipitation averages 42.2 Inches. Rosemont is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.9 °F | 41.5 °F | 3.02 in. |
| February | 25.4 °F | 45.0 °F | 2.4 in. |
| March | 32.1 °F | 53.4 °F | 3.55 in. |
| April | 42.0 °F | 65.6 °F | 3.37 in. |
| May | 51.8 °F | 74.3 °F | 4.27 in. |
| June | 60.6 °F | 82.6 °F | 3.93 in. |
| July | 65.1 °F | 87.2 °F | 4.05 in. |
| August | 63.2 °F | 85.4 °F | 3.23 in. |
| September | 56.2 °F | 78.7 °F | 4.43 in. |
| October | 44.8 °F | 67.5 °F | 3.43 in. |
| November | 34.8 °F | 55.9 °F | 3.06 in. |
| December | 27.9 °F | 45.4 °F | 3.43 in. |
| Annual | 44 °F | 65.2 °F | 42.17 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°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 |