5-day weather forecast for Alton, Illinois
Today
55°
81°
Chance Thunderstorms
Tuesday
49°
70°
Mostly sunny
Wednesday
60°
79°
Chance Thunderstorms
Thursday
61°
82°
Chance Thunderstorms
Friday
59°
78°
Mostly cloudy
Click on a forecast to see the forecast trend for that day
Weather forecast accuracy for Grafton, Illinois
| National Weather Service | 81.00% |
| The Weather Channel | 77.85% |
| Intellicast | 77.37% |
| NWS Digital Forecast | 76.74% |
| Accuweather | 69.15% |
| MyForecast | 68.67% |
| 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
It rained 57% of the time in Grafton last year when Accuweather's icon forecasts called for precipitation, and 12% of the time when they did not.