The official National Weather Service forecast for Saint Ignatius — 47.3199°N, 114.094°W, 21.8 miles from I-90.
| Lake County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 32 | 35 | 45 | 53 | 63 | 70 | 82 | 80 | 69 | 53 | 39 | 32 | 54 |
| Avg low °F | 20 | 20 | 26 | 31 | 39 | 45 | 51 | 50 | 43 | 33 | 26 | 20 | 34 |
| Precip in | 2.3 | 2.1 | 2.0 | 2.2 | 2.6 | 2.9 | 0.9 | 1.1 | 1.6 | 2.1 | 2.4 | 2.6 | 24.8 |
1996–2025 normals for Lake County — the climate division Saint Ignatius sits in. All-time county record high 99.2°F (2018-08-11); record low -30.4°F (2024-01-14). Source: NOAA / National Weather Service.