Seattle is home to five professional sports teams:

Mariners Baseball
In 1977 the American League Mariners played their first home game, against the California Angels in the now-defunct Kingdome. Today the three-time Western Division champs (1995, 1997, 2001) play in Safeco Field, a modern ball field influenced by the traditions and history of baseball. Baseball season runs from April through September.
seattle.mariners.mlb.com

Seahawks Football
Seahawks fans are still pumped up from the team's trip to the XL Superbowl in January 2006 as the National Football Conference champions. The Hawks started as an expansion team in 1976, playing in the Kingdome until it was demolished, making way for the Hawks' present home, Qwest Field. The Hawks play from September through December.
seahawks.com

Sounders Soccer
Started in 1974 under the North American Soccer League (NASL), the Sounders enjoyed sell-out crowds and won two conference championships, but folded in 1983. The team was reborn 11 years later. The Sounders won the Western Conference championship (2004) and were A-League champions twice (1995, 1996). In 2005 the team was the United Soccer League First Division champions. The Sounders play at Qwest Field from April through September.
seattlesounders.net

Storm Basketball
The Storm began in 2000 and by 2004 won the Women's National Basketball Association Championship, Seattle's first professional championship in 25 years. In 2005 the team won 20 games for the second straight season before ending in the first round of the playoffs. The Storm plays in KeyArena from May through August.
wnba.com/storm

Thunderbirds Hockey
The Thunderbirds joined the Western Hockey League as the Seattle Breakers in the 1977-78 season, then changed their name to the Thunderbirds for the 1985-86 season. The team won the WHL's Western Conference Championship in 1997 and the U.S. Division Championship in 2003. The Thunderbirds play in the KeyArena from October through March.
seattlethunderbirds.com