Recent National Weather Service and model guidance for Atlanta indicate an overnight low near 70–72°F on September 21, 2026, under partly cloudy skies with light winds and only a modest chance of late thunderstorms. This range aligns with the market’s dominant 72–73°F outcome at 88.5% implied probability, reflecting the absence of strong cold-air advection or clear-sky radiational cooling that could drop readings further. Dew points near 70°F and high humidity are limiting overnight temperature falls, while the 65°F-or-below market at 50% appears driven by residual uncertainty in precipitation timing and any localized cooling pockets. Updated model runs and the next NWS forecast discussion will provide the final observational confirmation as the calendar day closes.