Okay, okay. Winter dog park is the same as all-seasons dog park. It's really just going in the winter. But as long as you're bundled up, you can still have a good time, burn off some energy, and give them some much-needed socialization, especially if they tend to get stuck inside.
Southeast of Seattle you'll find North Bend and in it, there is an old logging camp turned ghost town. At its peak, it held about a thousand people before several geographical and man-made factors forced it to be abandoned. It's pretty creepy during the warmer months, but add in the somewhat lifeless nature of the colder months, plus the additional quiet and you've got yourself a great creepy spot to check out in winter, the perfect hike-able distance from civilization for you and your dog.
It's a food truck for dogs! They operate year-round outside of spare vacation days and have tons of options. They even have a hand-fed delivery hole for skittish dogs so just a hand with a treat pops out instead of being paired with an intimidating face!