The official National Weather Service forecast for Andover — 45.4102°N, 97.9026°W, 41.5 miles from I-29.
| Day County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 21 | 25 | 38 | 53 | 66 | 77 | 82 | 80 | 72 | 56 | 40 | 26 | 53 |
| Avg low °F | 3 | 5 | 18 | 31 | 44 | 55 | 60 | 58 | 49 | 35 | 22 | 9 | 32 |
| Precip in | 0.5 | 0.6 | 1.0 | 2.1 | 3.2 | 3.6 | 3.3 | 3.0 | 2.3 | 2.3 | 0.7 | 0.8 | 23.4 |
1996–2025 normals for Day County — the climate division Andover sits in. All-time county record high 103.1°F (2006-07-16); record low -38.8°F (1994-02-09). Source: NOAA / National Weather Service.