The official National Weather Service forecast for Rock Rapids — 43.4272°N, 96.1759°W, 14.8 miles from I-90.
| Lyon County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 26 | 30 | 44 | 58 | 70 | 81 | 84 | 81 | 76 | 61 | 45 | 30 | 57 |
| Avg low °F | 8 | 11 | 24 | 34 | 47 | 58 | 62 | 59 | 51 | 38 | 24 | 13 | 36 |
| Precip in | 0.7 | 0.8 | 1.5 | 2.9 | 3.9 | 4.8 | 3.2 | 3.1 | 3.0 | 2.3 | 1.2 | 1.0 | 28.4 |
1996–2025 normals for Lyon County — the climate division Rock Rapids sits in. All-time county record high 105.1°F (1988-06-22); record low -31.9°F (1970-01-19). Source: NOAA / National Weather Service.