Union Bridge, Maryland has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.5 °C (low) to 18.2 °C (high). Annual precipitation averages 1142.2 Millimeters. Union Bridge 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.9 °C | 4.6 °C | 83.31 mm |
| February | -4 °C | 6.6 °C | 66.55 mm |
| March | -0.3 °C | 11.4 °C | 97.03 mm |
| April | 5.2 °C | 18.4 °C | 88.9 mm |
| May | 10.7 °C | 23.4 °C | 104.14 mm |
| June | 15.8 °C | 28.2 °C | 103.63 mm |
| July | 18.5 °C | 30.7 °C | 110.74 mm |
| August | 17.4 °C | 29.5 °C | 88.14 mm |
| September | 13.5 °C | 25.8 °C | 122.17 mm |
| October | 7.1 °C | 19.3 °C | 99.57 mm |
| November | 1.3 °C | 12.9 °C | 83.57 mm |
| December | -2.2 °C | 7.1 °C | 94.49 mm |
| Annual | 6.5 °C | 18.2 °C | 1142.24 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |