Cynthiana, Kentucky has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.6 °C (low) to 18.8 °C (high). Annual precipitation averages 1212.3 Millimeters. Cynthiana is located in USDA Plant Hardiness Zone 6b. 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 | 5.1 °C | 85.85 mm |
| February | -3.5 °C | 7.5 °C | 88.14 mm |
| March | 0.3 °C | 12.7 °C | 117.6 mm |
| April | 5.7 °C | 19.1 °C | 113.28 mm |
| May | 11.5 °C | 24.1 °C | 129.54 mm |
| June | 16.1 °C | 28.6 °C | 123.44 mm |
| July | 18.3 °C | 30.6 °C | 124.46 mm |
| August | 17.3 °C | 29.9 °C | 81.53 mm |
| September | 13.2 °C | 26.8 °C | 84.84 mm |
| October | 6.7 °C | 20.6 °C | 81.28 mm |
| November | 0.8 °C | 13 °C | 81.53 mm |
| December | -2.6 °C | 7.3 °C | 100.84 mm |
| Annual | 6.6 °C | 18.8 °C | 1212.33 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |