Fall weather is taking control in the Chicago area as frosty nights and chilly days become more frequent. Thursday’s official 54-degree high in Chicago was the city’s lowest since May 6 when the mercury peaked at 53 degrees. Even chillier air is headed to the city, and by next Monday and Tuesday Chicago should record its first sub-50-degree highs since a 41-degree high on April 27. Overnight lows are more frequently headed to near or below freezing across most of the Chicago area, except for locations in the heart of Chicago and along the immediate lakeshore. While Tuesday and Wednesday’s rainfall brought some much-needed moisture, October rainfall totals are still below normal. No organized rainfall is expected in coming days, though with an unstable atmosphere in place, the product of the cold air aloft, scattered afternoon rain showers will develop. The fall chill will be persistent with Chicago area temperatures expected to remain below normal through much of next week before some warmer weather arrives.