Green Valley, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.1 °C (low) to 18.3 °C (high). Annual precipitation averages 1151.9 Millimeters. Green Valley is located in USDA Plant Hardiness Zone 7a. 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 | -4.2 °C | 5.2 °C | 79.25 mm |
| February | -3.4 °C | 6.9 °C | 68.83 mm |
| March | 0.3 °C | 11.8 °C | 98.55 mm |
| April | 5.7 °C | 18.6 °C | 87.88 mm |
| May | 11.3 °C | 23.4 °C | 110.49 mm |
| June | 16.3 °C | 28.1 °C | 114.81 mm |
| July | 19.1 °C | 30.5 °C | 110.74 mm |
| August | 17.8 °C | 29.4 °C | 88.39 mm |
| September | 14.1 °C | 25.8 °C | 114.81 mm |
| October | 7.6 °C | 19.3 °C | 99.82 mm |
| November | 1.9 °C | 13.1 °C | 84.84 mm |
| December | -1.7 °C | 7.4 °C | 93.47 mm |
| Annual | 7.1 °C | 18.3 °C | 1151.88 mm |
| 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 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |