Castalian Springs, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 20.8 °C (high). Annual precipitation averages 1372.1 Millimeters. Castalian Springs 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.7 °C | 8.1 °C | 109.47 mm |
| February | -1.3 °C | 10.7 °C | 120.14 mm |
| March | 2.5 °C | 15.7 °C | 124.97 mm |
| April | 7.2 °C | 21.1 °C | 125.22 mm |
| May | 12.8 °C | 25.6 °C | 139.45 mm |
| June | 17.6 °C | 29.7 °C | 112.52 mm |
| July | 19.8 °C | 31.4 °C | 123.44 mm |
| August | 19.2 °C | 31.2 °C | 101.09 mm |
| September | 14.9 °C | 28.1 °C | 98.04 mm |
| October | 8.1 °C | 22.2 °C | 93.22 mm |
| November | 2.2 °C | 15.3 °C | 98.04 mm |
| December | -0.7 °C | 10.1 °C | 126.49 mm |
| Annual | 8.3 °C | 20.8 °C | 1372.09 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 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |