Persistent cloud cover, widespread rain, and southerly winds are holding Seattle's overnight minimum near the mid-50s on September 13, with National Weather Service guidance and multiple forecast models converging on lows of 53–57°F. The marine layer and Puget Sound's moderating influence limit radiative cooling under overcast skies, while the ongoing precipitation and 8–12 mph breezes add further insulation. Historical September averages near 53.5°F provide context, yet the current synoptic pattern favors slightly milder readings than the long-term norm. Traders therefore cluster probabilities tightly around the 54–57°F range, with modest weight on the 52–53°F bin reflecting residual uncertainty in exact timing of any clearing or wind shift before dawn. Updated model runs and official observations through the night remain the key near-term catalysts.