Forecast uncertainty in National Weather Service and ensemble model guidance on cloud cover, afternoon convection, and lake breeze effects is driving the tight clustering of market-implied odds around 78–83°F for Chicago’s August 15 high, with 80–81°F and 82–83°F leading at roughly 25% and 24%. Recent cool, cloudy conditions on August 14 have moderated temperatures below mid-August normals near 83°F, while limited moisture and variable steering patterns keep intensification potential modest. Traders are weighing the balance between partial clearing that could allow readings near 82°F and lingering showers or thicker cloud decks favoring the lower end of the range. Updated model runs and NWS short-term forecasts expected later today will likely refine these probabilities ahead of resolution.