The official National Weather Service forecast for Erwin — 35.3268°N, 78.6761°W, 6.1 miles from I-95. Forecasts here are written by NWS RAH, this county’s forecast office.
| Harnett County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 53 | 57 | 65 | 74 | 81 | 88 | 90 | 88 | 83 | 74 | 64 | 56 | 73 |
| Avg low °F | 31 | 34 | 40 | 49 | 57 | 66 | 70 | 69 | 62 | 50 | 40 | 34 | 50 |
| Precip in | 3.4 | 3.1 | 3.5 | 3.5 | 3.6 | 4.3 | 5.5 | 5.0 | 5.5 | 2.9 | 3.2 | 3.6 | 47.1 |
1996–2025 normals for Harnett County — the climate division Erwin sits in. All-time county record high 103.7°F (1952-07-23); record low -4.3°F (1985-01-21). Source: NOAA / National Weather Service.