Recent National Weather Service and ensemble model guidance point to overnight lows near 77–79°F in Austin on August 21, driven by a strong subtropical ridge maintaining light winds, elevated dew points, and limited radiative cooling under partly cloudy skies. These conditions suppress the typical 4–6°F drop below the prior evening’s temperature that occurs on drier nights. With historical August minima averaging 74–75°F, the current setup favors values at the upper end of the normal range, producing closely matched market-implied probabilities across the 76–79°F bins as traders weigh minor differences among model runs for boundary-layer moisture and wind. Updated forecasts tonight will refine the exact minimum before resolution.