The official National Weather Service forecast for South Carthage — 36.242°N, 85.9519°W, 4.3 miles from I-40.
| Smith County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 48 | 52 | 62 | 71 | 79 | 86 | 89 | 88 | 83 | 73 | 61 | 52 | 70 |
| Avg low °F | 28 | 32 | 38 | 46 | 55 | 63 | 68 | 66 | 59 | 47 | 37 | 32 | 48 |
| Precip in | 4.6 | 5.2 | 5.0 | 4.8 | 5.1 | 4.8 | 4.8 | 3.7 | 3.7 | 3.3 | 3.6 | 5.0 | 53.6 |
1996–2025 normals for Smith County — the climate division South Carthage sits in. All-time county record high 107.0°F (1952-07-28); record low -16.5°F (1985-01-21). Source: NOAA / National Weather Service.