The next few days will see temperatures in the Chicago area average some 7 to 10 degrees below normal.
A cold flow aloft originating in northern and central Canada will combine with persistent surface low pressure just to our east generating a cooling north to northeasterly low-level flow the length of Lake Michigan’s relatively cool 55 to 60-degree waters. Subsequently a string of daytime highs in the 70s will probably persist here into mid-week.
Sunday could well be the chilliest day of the week ahead with gusty northeast winds restricting afternoon highs to the mid to upper 60s along the Illinois Lake Michigan shoreline and beaches and just the middle 70s well inland.
Low-level winds will finally shift to the south Thursday and continue into next weekend, signaling a return of warmer and increasingly more humid air. At this point in time, it looks like our July 4th should be an almost “typical” early July day here with high temperatures in the lower 80s, some building cumulus clouds in the afternoon and the possibility of isolated late-day or evening thunderstorms affecting perhaps 10 percent of the area.
By next Saturday, high humidity and 90-degree readings could be back in the picture.