The official National Weather Service forecast for Blackville — 33.3579°N, 81.2707°W, 29.3 miles from I-26. Forecasts here are written by NWS CAE, this county’s forecast office.
| Barnwell County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 59 | 63 | 70 | 77 | 84 | 90 | 92 | 91 | 86 | 77 | 68 | 61 | 76 |
| Avg low °F | 35 | 38 | 44 | 51 | 59 | 67 | 70 | 70 | 64 | 53 | 42 | 37 | 52 |
| Precip in | 3.8 | 3.7 | 3.9 | 3.3 | 3.8 | 5.1 | 5.3 | 5.1 | 4.0 | 2.6 | 2.7 | 3.9 | 47.2 |
1996–2025 normals for Barnwell County — the climate division Blackville sits in. All-time county record high 105.7°F (2012-07-01); record low -0.4°F (1985-01-21). Source: NOAA / National Weather Service.