Latest National Weather Service guidance shows a robust late-season cold front driving unseasonably chilly conditions across the Front Range, with northerly flow and an Arctic air mass expected to limit Denver’s high on May 18 to the mid-40s °F. This places the day well below the 71 °F May climatological average and firmly inside the market’s dominant 61 °F-or-below bin. Model consensus from the GFS and ECMWF remains tightly clustered on this outcome, with only modest differences in boundary-layer mixing that are unlikely to push readings above 60 °F. A sudden warm-air advection or significant model shift in the next 48 hours could theoretically raise the high into the low 60s, but current observations and ensemble spreads make such a reversal improbable before the market resolves.