Jefferson, South Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.5 °C (low) to 23.2 °C (high). Annual precipitation averages 1177.3 Millimeters. Jefferson is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.1 °C | 12.4 °C | 100.58 mm |
| February | 1.3 °C | 14.4 °C | 84.58 mm |
| March | 4.9 °C | 18.7 °C | 98.04 mm |
| April | 9.7 °C | 23.9 °C | 88.14 mm |
| May | 14.7 °C | 27.7 °C | 83.31 mm |
| June | 19.1 °C | 31.4 °C | 111 mm |
| July | 21.2 °C | 33.1 °C | 114.3 mm |
| August | 20.6 °C | 32.1 °C | 115.06 mm |
| September | 17.3 °C | 29.1 °C | 110.49 mm |
| October | 10.6 °C | 23.9 °C | 87.88 mm |
| November | 4.7 °C | 18.3 °C | 84.84 mm |
| December | 1.7 °C | 13.9 °C | 99.06 mm |
| Annual | 10.5 °C | 23.2 °C | 1177.28 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |