 Car Wash and Express Detail, Alton Auto Butler, where every car gets the royal treatment. Mostly clear skies is the forecast. After an overnight low in the mid-60s, your Thursday should be a sunny day with a high in the mid-80s. Thursday night, mostly cloudy, a low around 70. Friday, mostly cloudy, a chance of showers and thunderstorms. During the afternoon, a high near 90 degrees. And on Saturday, a partly sunny day with a chance of showers and thunderstorms and a high in the low 90s.