Current forecast models from the National Weather Service indicate overnight lows in Denver clustering in the low-to-mid 50s Fahrenheit for September 16, driven by a weak high-pressure ridge promoting radiational cooling under partly cloudy skies at the city’s 5,280-foot elevation. Ensemble spreads in the GFS and ECMWF runs create the tight 52–57°F band holding the highest implied probabilities, with differences hinging on exact dew-point depression, boundary-layer wind speeds, and any late-day frontal passage that could limit surface cooling. Historical September climatology for Denver shows average minima near 50°F, so the current setup reflects a slightly milder pattern without strong cold-air advection. Traders are monitoring the next model cycle and local observations for any shift in cloud cover or humidity that could push the realized minimum outside the leading bins.