Oswego, South Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11 °C (low) to 23.9 °C (high). Annual precipitation averages 1213.1 Millimeters. Oswego is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.9 °C | 13.7 °C | 94.23 mm |
| February | 2.2 °C | 15.6 °C | 89.15 mm |
| March | 5.4 °C | 19.7 °C | 92.71 mm |
| April | 10.1 °C | 24.6 °C | 82.04 mm |
| May | 15.1 °C | 28.2 °C | 91.95 mm |
| June | 19.7 °C | 31.5 °C | 131.06 mm |
| July | 21.4 °C | 33.1 °C | 133.6 mm |
| August | 20.7 °C | 32.1 °C | 129.03 mm |
| September | 17.6 °C | 29.4 °C | 109.73 mm |
| October | 11.2 °C | 24.4 °C | 94.49 mm |
| November | 5.1 °C | 19.1 °C | 71.88 mm |
| December | 2.3 °C | 15 °C | 93.22 mm |
| Annual | 11 °C | 23.9 °C | 1213.09 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°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 |