The official National Weather Service forecast for Marlette — 43.327°N, 83.0802°W, 23 miles from I-69. Forecasts here are written by NWS DTX, this county’s forecast office.
| Sanilac County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 30 | 32 | 42 | 55 | 67 | 77 | 81 | 79 | 73 | 60 | 47 | 35 | 56 |
| Avg low °F | 17 | 17 | 26 | 35 | 45 | 56 | 60 | 59 | 52 | 42 | 32 | 24 | 39 |
| Precip in | 2.1 | 1.9 | 2.1 | 3.0 | 3.4 | 3.2 | 3.2 | 3.3 | 3.1 | 3.0 | 2.2 | 2.2 | 32.7 |
1996–2025 normals for Sanilac County — the climate division Marlette sits in. All-time county record high 98.5°F (1988-07-08); record low -20.3°F (2015-02-20). Source: NOAA / National Weather Service.