December 1, 8, 15:  Tuesday Quads begin.  Typically, this is a 3-round round robin, with players sorted by ratings.  However, December, with its  5 Tuesdays,  offers the possibilities of additional games, so a different format may occur, depending on the number of players and their wishes.  Chess.com rated.

December 3, 10, & 17:  Thursday Game in 15.  Play 3 games in an evening–try out different openings. Chess.com rated.

December 5 & 6:  PCC Winter Open Online.  This is a 4-round Swiss in 3 sections, so you will play others in a similar rating range. USCF Chess membership required.

December 19:  Third Saturday Blitz. 

See www.pdxchess.org for more information.