Middle River, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.1 °C (low) to 18.4 °C (high). Annual precipitation averages 1225.5 Millimeters. Middle River is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.6 °C | 5.7 °C | 86.61 mm |
| February | -1.9 °C | 6.9 °C | 72.64 mm |
| March | 1.9 °C | 11.3 °C | 109.73 mm |
| April | 7.8 °C | 17.9 °C | 93.98 mm |
| May | 13.2 °C | 23 °C | 108.2 mm |
| June | 18.4 °C | 28 °C | 114.05 mm |
| July | 21.3 °C | 30.6 °C | 114.05 mm |
| August | 20.4 °C | 29.7 °C | 105.66 mm |
| September | 16.6 °C | 26.1 °C | 120.9 mm |
| October | 10 °C | 19.6 °C | 112.01 mm |
| November | 4.1 °C | 13.4 °C | 84.84 mm |
| December | 0 °C | 8 °C | 102.87 mm |
| Annual | 9.1 °C | 18.4 °C | 1225.54 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |