The official National Weather Service forecast for Alton — 38.1226°N, 86.4178°W, 8.2 miles from I-64. Forecasts here are written by NWS LMK, this county’s forecast office.
| Crawford County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 42 | 47 | 57 | 68 | 76 | 84 | 87 | 86 | 81 | 69 | 56 | 46 | 67 |
| Avg low °F | 23 | 26 | 34 | 42 | 53 | 61 | 65 | 63 | 56 | 44 | 34 | 28 | 44 |
| Precip in | 3.9 | 3.7 | 5.0 | 5.5 | 5.5 | 4.6 | 5.0 | 3.2 | 3.7 | 3.6 | 3.9 | 4.0 | 51.6 |
1996–2025 normals for Crawford County — the climate division Alton sits in. All-time county record high 105.8°F (2012-06-30); record low -21.0°F (1994-01-19). Source: NOAA / National Weather Service.