A cold front crossing the Northeast on September 18 is ushering in cooler, drier air behind north-to-northeast winds, setting up the primary driver for NYC’s overnight low on the 19th. Official NWS guidance and model consensus point to partly cloudy skies with highs near 70°F and light winds allowing modest radiational cooling, favoring a minimum in the low-to-mid 60s°F—aligning with the market’s tight clustering around 62–65°F bins. Recent Central Park observations show a sharp drop from mid-70s daytime readings, consistent with the post-frontal air mass. Key variables differentiating the leading outcomes include exact cloud cover timing, dewpoint trends near 50–55°F, and boundary-layer mixing; any earlier clearing or lighter winds could push toward 60–61°F, while residual moisture might hold readings higher. Updated NWS briefings and overnight model runs will refine the range before resolution.