Chicago-area temperatures peaked in the upper 80s and lower 90s Wednesday and coupled with uncomfortable dew points in the 70s, produced heat indices of 100 to 105. The city’s official 93-degree high at O’Hare Airport made this the city’s hottest Fourth of July since 2012 when the mercury reached a scorching 102. While no organized thunderstorm activity occurred, scattered pop-up thunderstorms dotted the landscape, producing brief downpours. One heavy storm forced a brief shut down of the Naperville Rib Fest. Temperatures are expected to top the 90-degree mark again on Thursday, but thunderstorm activity is expected to be more widespread as a cold front moves through the area ushering in a noticeably cooler and less humid air mass for the weekend. Highs on Friday should range from the lower 80s inland to the lower 70s, courtesy of fresh northeast winds 10-20 mph. Seasonably warm, but comfortable conditions should prevail through the weekend before hot and humid conditions return next week.