A persistent northerly wind flow behind a coastal low-pressure system is the dominant driver keeping New York City’s September 26 high temperature in the low-to-mid 60s °F, well below the late-September climatological average near 73 °F. Official National Weather Service guidance and ensemble model consensus show widespread rain, gusts exceeding 40 mph, and thick cloud cover limiting daytime heating, with forecast highs clustered between 61 °F and 65 °F across Central Park, LaGuardia, and JFK observations. These conditions explain why the 60–65 °F bins together command over 75 % of market-implied probability. Minor model spread around exact thermal advection and timing of heaviest precipitation accounts for the tight clustering among the three leading outcomes; any late forecast shift in wind direction or rainfall duration could nudge the verified high across the 63–64 °F threshold.