The official National Weather Service forecast for Ennis — 45.3488°N, 111.7297°W, 37.6 miles from I-90.
| Madison County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 33 | 41 | 49 | 58 | 67 | 78 | 76 | 66 | 52 | 39 | 31 | 52 |
| Avg low °F | 14 | 13 | 20 | 26 | 34 | 41 | 48 | 46 | 39 | 30 | 20 | 14 | 29 |
| Precip in | 1.6 | 1.6 | 1.9 | 2.4 | 3.1 | 2.8 | 1.1 | 1.4 | 1.6 | 1.9 | 1.6 | 1.8 | 22.8 |
1996–2025 normals for Madison County — the climate division Ennis sits in. All-time county record high 93.4°F (2002-07-13); record low -35.3°F (1989-02-04). Source: NOAA / National Weather Service.