Persistent summer heat and high humidity over the Gulf Coast are anchoring overnight lows near 78–82°F in Houston, with National Weather Service guidance showing minimal diurnal cooling under light southerly flow and mostly clear skies. Ensemble model spreads create tight clustering around 72–83°F bins because small differences in cloud cover, boundary-layer mixing, or weak tropical moisture can shift the minimum by a few degrees. Historical August climatology places typical lows at 76–78°F, but the current ridge and lack of a frontal passage keep probabilities balanced across mid-70s to low-80s outcomes rather than favoring extremes. Updated short-range model runs tomorrow morning will refine the exact minimum before market resolution.