Harlan, Kentucky has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7 °C (low) to 19.5 °C (high). Annual precipitation averages 1301.5 Millimeters. Harlan 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 | -3.7 °C | 7.4 °C | 108.71 mm |
| February | -2.3 °C | 9.6 °C | 111.76 mm |
| March | 1.1 °C | 14.7 °C | 123.44 mm |
| April | 5.9 °C | 20.4 °C | 120.9 mm |
| May | 11.4 °C | 24.5 °C | 115.32 mm |
| June | 15.8 °C | 27.9 °C | 110.49 mm |
| July | 18.1 °C | 29.3 °C | 128.52 mm |
| August | 17.4 °C | 29.1 °C | 103.63 mm |
| September | 13.9 °C | 26.4 °C | 89.15 mm |
| October | 6.9 °C | 20.8 °C | 75.44 mm |
| November | 1.1 °C | 14.7 °C | 91.44 mm |
| December | -1.6 °C | 9.3 °C | 122.68 mm |
| Annual | 7 °C | 19.5 °C | 1301.48 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 | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |