The closely matched probabilities across 58–69°F ranges reflect substantial short-term forecast uncertainty for Chicago’s overnight low on September 8, as numerical weather models diverge on the timing and strength of an approaching cold front. Current GFS and ECMWF runs show varying solutions for surface high pressure and northerly flow, with potential for clearer skies and radiational cooling versus increased cloud cover that would moderate temperatures. Early September climatology places average lows near 60°F, but 2026 conditions feature above-normal warmth ahead of the front, keeping higher bins viable if advection persists. Traders are monitoring the next model cycles and National Weather Service updates for refined guidance on dew points and wind speeds, which directly influence minimum readings.