5-day weather forecast for Alton, Illinois
Today
63°
86°
Chance Thunderstorms
Thursday
69°
87°
Chance Thunderstorms
Friday
71°
91°
Chance Thunderstorms
Saturday
70°
88°
Chance Thunderstorms
Sunday
69°
88°
Chance Thunderstorms
Click on a forecast to see the forecast trend for that day
Weather forecast accuracy for Grafton, Illinois
| National Weather Service | 75.61% |
| The Weather Channel | 73.68% |
| NWS Digital Forecast | 71.64% |
| MyForecast | 70.83% |
| Accuweather | 67.90% |
| Intellicast | 61.51% |
| Intellicast | 74.43% |
| The Weather Channel | 74.43% |
| National Weather Service | 73.36% |
| NWS Digital Forecast | 71.72% |
| Accuweather | 71.37% |
| MyForecast | 70.45% |
ForecastAdvisor Fact
8.3% of National Weather Service's low temperature forecasts for Grafton were exactly right last month.