Persistent high pressure and a strong upper-level ridge over the southern Plains are sustaining elevated overnight lows in Austin, with National Weather Service guidance pointing to minima near 77–80 °F under mostly clear skies and light southerly flow. These conditions limit radiative cooling despite the diurnal cycle, as warm advection and elevated soil temperatures keep the boundary layer from dropping sharply. Recent model runs show minor spread in low-level moisture and wind speed that could shift the minimum by a degree or two, producing the tight clustering of market-implied probabilities around the 74–79 °F bins. Historical August averages near 75 °F provide context, yet the ongoing heat dome has consistently held recent lows in the upper 70s, leaving traders focused on any last-minute forecast adjustments before resolution.