Before we moved to the Southeast I belonged to the Seattle Radio Aero Club (now called the Snohomish Radio Aero Club http://www.sracinc.com/ ) for about twenty years. They have one of the best flying sites in the area and is located a few miles north of Snohomish. See image below. They are a great group and I highly recommend the club.

It is possible to fly year round but it can get pretty cool in the winter and some snow. The snow doesn’t say around very long though. I did fly while it was snowing a few times, got to keep it low and close in. We also flew on rain days by getting a flight in between the showers. Like the others said, Seattle rain is not really wet rain but it can create a lot of building time so our club had some extraordinary great builders.