80 Degrees Thursday, Then A Drastic Cool Down In Puget Sound

SEATTLE, WA - Eighty degrees in Seattle, 82 in Olympia and near Tacoma, high 70s in Snohomish County, and barely a cloud in sight - the forecast for Thursday looks downright summery.

But enjoy it, because temperatures will drop starting Friday. Rain will move in on Saturday.

On Friday, temperatures will be about 15 degrees cooler, topping out at 65 in the Seattle area. On Saturday, it'll be about 25 degrees cooler than Thursday - and there's about a 70 percent chance of rain.

Why the drastic change? According to meteorologists, it's the wind. Puget Sound gets warm when easterly winds hit the Cascades and flow downslope.

"Easterly flow pushes the cool marine influence offshore and produces downslope warming on the west side of terrain (like the Cascades and coastal mountains). The coast enjoys the downslope warming benefits of two mountain barriers and thus gets very warm," University of Washington meteorologist Cliff Mass wrote in a blog post about this week's warm temps.

It will be cooler on Friday and through the weekend, Mass explained, because of a current of cool marine air pushing up into Puget Sound.

Image courtesy National Weather Service