A strong El Niño event, with NOAA assigning over 90% odds of a very strong or super episode through winter, represents the dominant factor shaping trader sentiment on the timing of the first measurable snowfall (0.1 inch or greater) in tracked U.S. cities. Sea-surface temperature anomalies near record levels favor warmer and drier fall conditions across much of the northern and central United States, shifting probabilities toward later-than-climatological first snow dates in places such as Denver, Indianapolis, and the Upper Midwest. As of late September 2026, no qualifying snowfall has been recorded at official National Weather Service stations in major market cities, consistent with historical patterns where northern Rockies and Plains locations typically see initial flakes in mid-to-late October. Traders monitor upcoming NOAA Climate Prediction Center outlooks, National Weather Service model runs, and early cold-air intrusion signals that could accelerate or further delay accumulation thresholds.