Recent model consensus and persistent warm, humid air masses have anchored trader expectations for NYC's August 20 overnight low near 70–73°F, where the two leading bins each command 37% implied probability. High dew points near 70°F and limited radiative cooling under partly cloudy skies or urban heat-island effects are the primary drivers keeping minima from dropping into the upper 60s, while any increase in wind or clearer skies could nudge readings toward the 74–75°F bin that holds 27.5%. National Weather Service guidance and ensemble spreads show only modest day-to-day variability at this stage of the season, producing the tight clustering around these three outcomes.