Trader consensus centers on 80–83°F for Chicago’s August 15 high, reflecting model agreement on a transitional pattern with scattered showers and thunderstorms expected to limit full solar heating. National Weather Service guidance highlights an active regime with mesoscale convective systems and periods of cloud cover, which historically caps daytime maxima 2–4°F below clear-sky potential near Lake Michigan. Lake-breeze moderation, wind shifts, and precipitation timing introduce the narrow spread between the 80–81°F and 82–83°F bins; drier breaks could allow brief warming toward the upper end, while persistent overcast or earlier convection would favor the lower. Short-term model runs and afternoon updates will refine these thresholds ahead of market resolution.