New Castle, Kentucky has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.8 °C (low) to 18.4 °C (high). Annual precipitation averages 1261.6 Millimeters. New Castle 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 | -5 °C | 4.8 °C | 91.44 mm |
| February | -3.6 °C | 7.2 °C | 90.68 mm |
| March | 0.6 °C | 12.5 °C | 113.54 mm |
| April | 6.3 °C | 18.7 °C | 123.7 mm |
| May | 12.2 °C | 23.5 °C | 137.41 mm |
| June | 16.2 °C | 28.7 °C | 125.98 mm |
| July | 18.3 °C | 30.2 °C | 113.03 mm |
| August | 17.6 °C | 29.3 °C | 92.2 mm |
| September | 13.7 °C | 26.3 °C | 92.2 mm |
| October | 6.9 °C | 20.4 °C | 89.66 mm |
| November | 1.3 °C | 12.8 °C | 88.9 mm |
| December | -2.5 °C | 6.9 °C | 102.87 mm |
| Annual | 6.8 °C | 18.4 °C | 1261.61 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 |