Persistent warm and humid subtropical air across South Florida produced overnight lows in the upper 70s at Miami International Airport (KMIA) on June 12, aligning with National Weather Service climatological normals and model consensus that kept the lowest reading in the 78–79 °F bin. Typical early-June conditions—high dew points near 75 °F, light winds, and minimal radiational cooling under partly cloudy skies—prevented deeper drops, consistent with the absence of any cool-air advection or clear-sky outbreaks in recent NWS guidance. The 99.7 % market-implied probability reflects traders’ confidence in these stable atmospheric patterns and the station’s verified observational record. A rare, sharp frontal passage or unexpected clear, calm night could have lowered readings into the mid-70s, but no such development materialized within the 48-hour forecast window.