The official National Weather Service forecast for Ontonagon — 46.871°N, 89.314°W, 226.1 miles from I-75. Forecasts here are written by NWS MQT, this county’s forecast office.
| Ontonagon County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 23 | 27 | 38 | 50 | 64 | 74 | 78 | 76 | 69 | 55 | 40 | 27 | 52 |
| Avg low °F | 6 | 6 | 15 | 27 | 39 | 49 | 54 | 53 | 47 | 35 | 25 | 13 | 31 |
| Precip in | 2.1 | 1.6 | 1.9 | 3.0 | 3.0 | 3.4 | 3.5 | 3.2 | 3.4 | 3.5 | 2.5 | 2.2 | 33.3 |
1996–2025 normals for Ontonagon County — the climate division Ontonagon sits in. All-time county record high 98.3°F (1988-07-08); record low -35.7°F (1996-02-03). Source: NOAA / National Weather Service.