**Persistent subtropical warmth and limited nocturnal cooling under clear to mostly clear skies are anchoring trader expectations for an 80-81°F low in Miami on August 18.** Official National Weather Service forecasts show overnight lows stabilizing near 80–82°F through the period, consistent with August climatology in which Miami’s humid marine air mass and urban heat island typically prevent temperatures from falling below the upper 70s. Recent observations confirm this pattern, with minimums of 81–82°F recorded on preceding nights amid light southeast winds and heat indices above 105°F. Model consensus from NWS and other sources shows no incoming cold front or increased cloud cover that would enhance radiative cooling, keeping implied probabilities highest for the 78–81°F range. Any modest downward revision in forecasts could shift sentiment toward 78–79°F, while sustained clear conditions reinforce the current 80–81°F lead.