LEAVENWORTH, WA. In the heart of the Cascade Mountain range, you will find the small town of Leavenworth, WA. Since 1988, Leavenworth has been celebrating Oktoberfest and each year the party gets a little bigger and a lot better. Oktoberfest is an event that takes place during three weekends in October. Be entertained by musicians and bands that travel as far as from Germany to perform. Enjoy a weekend of good music, great food, cold beer, and a lot of fun.