Harrington, Delaware has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 45.7 °F (low) to 65.9 °F (high). Annual precipitation averages 46.8 Inches. Harrington 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 | 25.3 °F | 43.5 °F | 3.43 in. |
| February | 26.5 °F | 46.0 °F | 3.03 in. |
| March | 33.4 °F | 53.5 °F | 4.17 in. |
| April | 43.5 °F | 64.9 °F | 3.58 in. |
| May | 53.2 °F | 73.8 °F | 3.95 in. |
| June | 62.4 °F | 82.7 °F | 4.19 in. |
| July | 67.3 °F | 87.2 °F | 4.32 in. |
| August | 65.1 °F | 85.3 °F | 4.57 in. |
| September | 58.9 °F | 79.5 °F | 4.38 in. |
| October | 46.9 °F | 68.3 °F | 3.99 in. |
| November | 36.4 °F | 57.7 °F | 3.25 in. |
| December | 29.9 °F | 48.2 °F | 3.93 in. |
| Annual | 45.7 °F | 65.9 °F | 46.79 in. |
| 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 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |