The official National Weather Service forecast for South Sioux City — 42.4739°N, 96.4136°W, 1.4 miles from I-29.
| Dakota County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 30 | 35 | 48 | 61 | 72 | 83 | 86 | 83 | 78 | 64 | 48 | 34 | 60 |
| Avg low °F | 11 | 14 | 26 | 36 | 48 | 60 | 64 | 61 | 52 | 39 | 26 | 15 | 38 |
| Precip in | 0.7 | 0.8 | 1.6 | 2.9 | 4.0 | 4.5 | 3.2 | 3.6 | 2.6 | 2.2 | 1.2 | 1.0 | 28.3 |
1996–2025 normals for Dakota County — the climate division South Sioux City sits in. All-time county record high 106.3°F (1988-06-22); record low -29.5°F (2021-02-16). Source: NOAA / National Weather Service.