The official National Weather Service forecast for Hyannis — 42.0005°N, 101.7618°W, 61 miles from I-80.
| Grant County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 37 | 39 | 50 | 59 | 69 | 81 | 87 | 85 | 77 | 63 | 50 | 39 | 61 |
| Avg low °F | 14 | 15 | 24 | 32 | 42 | 53 | 59 | 57 | 47 | 34 | 23 | 15 | 35 |
| Precip in | 0.4 | 0.6 | 1.0 | 2.3 | 3.5 | 3.4 | 2.9 | 2.3 | 1.7 | 1.3 | 0.5 | 0.4 | 20.3 |
1996–2025 normals for Grant County — the climate division Hyannis sits in. All-time county record high 105.5°F (2006-07-17); record low -34.7°F (1989-12-22). Source: NOAA / National Weather Service.