**Forecast consensus for Denver’s overnight low on September 20, 2026, centers on 49–53 °F, aligning with the market’s tight clustering around the 50–55 °F bins.** Official National Weather Service point forecasts and local outlooks (Denver7, Weather Atlas) indicate scattered thunderstorms or partly cloudy skies on the 19th–20th, followed by light northeast winds and dew points near 50–52 °F that limit radiative cooling. This produces an expected minimum in the upper 40s to low 50s, consistent with the 30 % probability on 50–51 °F and the combined ~44 % on the adjacent 52–53 °F and 54–55 °F ranges. Key differentiating factors include the timing and extent of cloud cover, which modulates longwave radiative loss, and subtle variations in boundary-layer mixing from light winds. Higher-resolution models can shift the exact minimum by 1–3 °F depending on whether skies clear fully before dawn or retain enough moisture for a slightly warmer floor. Historical climatology (average low ~47.6 °F) provides context, but the current stable, post-frontal pattern lacks strong cold advection, keeping probabilities concentrated in the narrow 48–55 °F window rather than extremes. Upcoming model runs and NWS forecast updates through the evening of the 19th will likely refine these narrow bins.