Millsboro, Delaware has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.9 °C (low) to 18.8 °C (high). Annual precipitation averages 1206 Millimeters. Millsboro is located in USDA Plant Hardiness Zone 7b. 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 | -3.4 °C | 6.8 °C | 89.41 mm |
| February | -2.7 °C | 8.2 °C | 78.99 mm |
| March | 0.9 °C | 12 °C | 108.97 mm |
| April | 6.6 °C | 18.1 °C | 88.65 mm |
| May | 12 °C | 22.9 °C | 93.22 mm |
| June | 17.2 °C | 27.8 °C | 103.38 mm |
| July | 19.8 °C | 30.3 °C | 109.98 mm |
| August | 18.7 °C | 29.3 °C | 122.43 mm |
| September | 15.4 °C | 26.2 °C | 109.73 mm |
| October | 8.7 °C | 20.4 °C | 109.98 mm |
| November | 2.6 °C | 14.4 °C | 86.36 mm |
| December | -0.9 °C | 9.4 °C | 104.9 mm |
| Annual | 7.9 °C | 18.8 °C | 1206 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°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 |