Traders assign the highest probabilities to 84–87°F outcomes for NYC's August 18 high because official forecast guidance and ensemble models indicate typical late-summer conditions under a ridge of high pressure, with southerly flow supporting daytime maxima near or slightly above the 83°F climatological average. Recent model runs show limited spread, with surface observations and upper-air data confirming dew points in the upper 60s to low 70s that favor modest heat retention without triggering strong convection or rapid cooling. The closely matched 84–85°F and 86–87°F bins reflect genuine uncertainty in exact peak timing and localized urban heat effects, while lower-probability tails account for possible model shifts or measurement variations at the official Central Park station before resolution.