The official National Weather Service forecast for Plymouth — 41.3437°N, 86.3097°W, population 12,279, 26.2 miles from I-90. Forecasts here are written by NWS IWX, this county’s forecast office.
| Marshall County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 32 | 36 | 48 | 61 | 72 | 81 | 84 | 82 | 77 | 64 | 49 | 37 | 60 |
| Avg low °F | 17 | 20 | 28 | 37 | 48 | 59 | 62 | 60 | 53 | 42 | 32 | 23 | 40 |
| Precip in | 2.6 | 2.3 | 2.6 | 3.6 | 4.4 | 4.3 | 4.2 | 4.0 | 3.0 | 3.3 | 2.6 | 2.6 | 39.5 |
1996–2025 normals for Marshall County — the climate division Plymouth sits in. All-time county record high 102.4°F (2012-07-07); record low -22.3°F (1994-01-19). Source: NOAA / National Weather Service.