Castalia, North Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.3 °C (low) to 21.6 °C (high). Annual precipitation averages 1210.3 Millimeters. Castalia is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.2 °C | 10.4 °C | 90.93 mm |
| February | -0.3 °C | 12.3 °C | 72.14 mm |
| March | 3.2 °C | 16.3 °C | 106.43 mm |
| April | 8.3 °C | 21.9 °C | 89.66 mm |
| May | 13.6 °C | 25.9 °C | 90.17 mm |
| June | 18.3 °C | 30.1 °C | 111.25 mm |
| July | 20.6 °C | 31.9 °C | 125.22 mm |
| August | 19.7 °C | 30.8 °C | 127.76 mm |
| September | 16.2 °C | 27.7 °C | 139.45 mm |
| October | 9.4 °C | 22.3 °C | 87.63 mm |
| November | 3.6 °C | 16.8 °C | 83.57 mm |
| December | 0.4 °C | 12.2 °C | 86.11 mm |
| Annual | 9.3 °C | 21.6 °C | 1210.32 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°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 |