Friday, was a reminder to Chicagoans that fall has actually arrived. The day’s chilly high of just 58 degrees marked the city’s first encounter with sub-60-degree weather since May 21, when the high reached just 54 degrees and it was the first day with below normal temperatures here in nearly a month. Temperatures will rebound into the lower and middle 60s Saturday, courtesy of increasing south winds, but showers and even a few thunderstorms will develop late Saturday and Saturday night as a cold front sweeps through the area. In contrast to the city’s recent heavy rain episodes, the expected rainfall is expected to be on the light side, with most totals forecast to be less than one-quarter inch. Sprawling high pressure will move into the Midwest in the wake of the front bringing sunny and milder weather to the city for the early part of next week, with highs forecast to return to the lower 70s by Wednesday.