Conflicting model ensembles are driving the near-even split between sub-63°F and 82°F-plus outcomes for New York City’s lowest temperature on May 20. Recent GFS and ECMWF runs diverge sharply on the arrival and strength of a potential cold front versus persistent southerly flow, with one cluster favoring overnight radiational cooling under clearing skies and northwest winds that could drop readings into the upper 50s, while warmer scenarios maintain a stable air mass and cloud cover that limits cooling. Historical May climatology shows typical lows near 55–60°F, yet the current spread reflects genuine forecast uncertainty four days out, with updated National Weather Service guidance and ensemble means expected to narrow the range as the period approaches.