Official forecasts from the National Weather Service place Chicago’s August 4 high near 85°F under mostly sunny skies with light southerly flow, aligning closely with the market’s heaviest concentration on the 84–87°F bins. Lake Michigan’s moderating influence and typical mid-summer lapse rates limit rapid warming, while recent model runs show minimal deviation from climatological normals around 82–84°F. A weak trough approaching from the northwest introduces slight uncertainty for late-day mixing, keeping the 82–83°F outcome in play but secondary. No significant heat advection or subsidence is indicated, supporting the current trader consensus around the mid-80s. Updated NWS briefings and afternoon observations will provide the next resolution-relevant data points.