As runners line up for the Chicago Marathon on Sunday morning, temperatures will rest in the almost ideal middle 50s while a gusty southwest wind will enable most of their early route headed north. The subsequent turn south will be a real challenge, as headwinds will be strengthening with temperatures rising through the 60s into the lower 70s by late morning or early afternoon. During the afternoon, winds will peak around 30 mph and temperatures top out near 80 degrees.
A cold front will approach from the northwest Sunday night, passing through the Chicago area early Monday. Skies will be partly sunny with temperatures leveling off around 70 degrees about midday Monday — setting the stage for gusty northwest winds and slowly falling temperatures during the third game of the Cubs-Cardinals National League Division Series.
A buckle in the jet stream will set up a northwest flow over the Midwest and western Great Lakes for the remainder of the workweek ahead. A low-pressure disturbance aloft is expected to bring cloudiness and scattered light showers Thursday night into Friday morning, followed by a chilly high-pressure air mass that looks to hold daytime highs in the 50s Friday and Saturday afternoons. Then as that high pressure moves east, southerly flow should bring a renewed warming trend into the next week.