Persistent heat dome conditions and high humidity across Southeast Texas have limited overnight radiative cooling, anchoring Houston's minimum temperatures near the long-term August average of 78°F. Official forecasts from the National Weather Service and AccuWeather project lows of 79–81°F for August 21 under mostly clear skies and light winds, consistent with recent observations showing overnight readings in the upper 70s. This scientific consensus, reinforced by model agreement on continued southerly flow and absence of frontal passages, underpins the market's overwhelming 93.5% implied probability for the 78–79°F bin. A realistic challenge would require an unforecasted increase in cloud cover, localized heavy precipitation, or rapid boundary passage—developments not supported by current guidance but potentially visible in updated model runs or real-time observations before midnight.