**Trader sentiment on the lowest temperature in Atlanta on August 21, 2026, centers on overnight lows in the low-to-mid 70s°F, with the 72–77°F bins capturing over 85% of implied probability.** National Weather Service guidance and model consensus point to a minimum near 71–75°F at Hartsfield-Jackson Atlanta International Airport (KATL), reflecting a continuation of elevated readings driven by high dew points, limited radiational cooling under partly to mostly cloudy skies, and a chance of showers or thunderstorms through the night. Persistent humidity and weak steering flow have kept temperatures above late-August climatological norms (average low near 70°F), while urban heat retention and light winds further moderate the drop after daytime highs near 98°F. The tight spread among leading outcomes arises from uncertainty in cloud cover timing and storm impacts, which can suppress or enhance overnight cooling by several degrees; clearer breaks could push readings toward the lower bins, while sustained moisture would favor the upper ones. Official NWS forecast updates and real-time KATL observations remain the key near-term catalysts for any shifts in market-implied odds.