National Weather Service guidance and ensemble model consensus for Atlanta on August 21 project a high in the low-90s under lingering high pressure and southerly flow, with afternoon dew points near 70°F supporting limited mixing and heat indices above 100°F. Scattered convection expected after peak heating introduces the main uncertainty, as any earlier or more widespread storms could suppress readings into the upper 80s while clearer skies favor 94–95°F. This spread explains the tight clustering of trader-implied probabilities around the 90–93°F bins versus lower odds on extremes, reflecting climatological late-August norms near 89°F and the resolution sensitivity of official KATL observations.