National Weather Service ensemble guidance and recent model runs from the GFS and ECMWF currently favor overnight lows in the upper 50s to low 60s for New York City on May 21, consistent with the market’s leading 58–59 °F and 60–61 °F bands. These probabilities reflect moderate radiative cooling expected under partly cloudy skies and light southerly flow, tempered by above-average humidity that limits temperature drops. Climatological baselines place typical mid-to-late May minima near 55 °F, yet recent days have shown 54–55 °F readings when clear conditions prevailed, explaining why lower bands such as 49 °F or below still carry meaningful probability if a stronger high-pressure ridge builds. Key variables that could shift outcomes include revisions to 48-hour forecasts and any late-arriving frontal moisture.