On Friday, an atmospheric front will move through the region, bringing rain, cloudy skies and gusty winds in the morning. Showers will taper off to isolated bursts in the afternoon. Along the shores of Puget Sound and near the Strait of Juan de Fuca, gusts could reach 25–30 mph (40–48 km/h). The rain will not be heavy, with total accumulation of around 2.5 millimeters, although a convergence zone could bring slightly more precipitation to the Sea-Tac Airport area.
By Saturday, the rain will quickly move out, giving way to cooler and drier conditions. Highs will reach roughly 14–17°C, while overnight temperatures in Seattle will fall to 7–8°C. Near the foothills of the eastern Cascades, temperatures around 3–4°C could bring frost. Similar weather will continue Sunday and Monday, at times with sunnier mornings and temperatures near 16°C. This cool autumn weekend will be a good time to visit areas where the foliage is changing especially brightly; wetter and windier conditions are expected in the second half of October.
Based on: Seattle weather: Rainy kickoff before temperatures begin to cool