Recent National Weather Service and ensemble model guidance points to a cooler-than-average pattern across the Northeast, driven by a weak polar vortex that has kept temperatures several degrees below seasonal norms through mid-May. For New York City on May 20, overnight lows are projected in the low-to-mid 50s under partly cloudy skies and light northerly flow, supporting the elevated market-implied probability for readings at or below 63°F. Historical climatology places typical late-May minima near 55–60°F at Central Park, so any deviation from current model consensus—such as a stronger southerly return flow—could shift the outcome into the 66–69°F range. Updated short-range forecasts from NOAA will provide the next key data point for traders monitoring this temperature threshold.