The official National Weather Service forecast for Alton — 26.2873°N, 98.3133°W, 4.9 miles from I-2. Forecasts here are written by NWS BRO, this county’s forecast office.
| Hidalgo County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 72 | 76 | 82 | 87 | 92 | 97 | 97 | 99 | 94 | 88 | 80 | 73 | 86 |
| Avg low °F | 49 | 53 | 60 | 65 | 72 | 75 | 76 | 76 | 73 | 66 | 58 | 51 | 64 |
| Precip in | 0.8 | 0.8 | 1.3 | 1.4 | 2.5 | 2.7 | 2.7 | 1.8 | 4.5 | 2.3 | 1.5 | 1.0 | 23.3 |
1996–2025 normals for Hidalgo County — the climate division Alton sits in. All-time county record high 108.8°F (2024-05-10); record low 13.3°F (1962-01-12). Source: NOAA / National Weather Service.