According to a City of Seattle press release, expect cold, traffic, and a fuck-load of people:
The parade, with an expected turnout of 200,00 to 500,000 spectators, will begin at 11 a.m. and conclude with a rally at CenturyLink Field at 1:30 p.m. Travelers should expect roadway and transit delays throughout the day due to crowds and road closures, with spectators likely arriving well in advance of the event. Given the celebration’s unprecedented size, drivers and transit riders should anticipate heavy traffic congestion in downtown, Lake Union, Queen Anne, the stadium area and nearby highways. Metro and Sound Transit plan to use every available resource to accommodate what will likely be the largest parade in the city’s history.
The parade begins at Fourth Avenue and Denny Way, and heads south on Fourth Avenue to S Washington Street. From there it will proceed west to Second Avenue S, turn south on Second and then move into the North Lot at CenturyLink Field. Fourth Avenue and all cross streets from Third Avenue to Fifth Avenue will be closed to traffic starting at 10:30 a.m. and reopen after the parade passes, and Occidental Avenue will be closed at 8:30 a.m. “No parking” signs for the event are in place and prohibit parking along the route from 8:00 a.m. until 2:00 p.m. on Wednesday. More than 75,000 fans are expected to attend a ticketed rally in the stadium area after the parade, so sizable crowds and area delays will continue well after the parade concludes. Fans are encouraged to dress warmly and be prepared for delays.
Buses and trains are expected to be extremely crowded. Riders may encounter significant wait times and service delays. Some buses will be rerouted in Downtown Seattle. Riders should sign up to receive rider alert messages via e-mails or text message for their specific bus route or train.
Traffic this morning is heavier than normal, and fans are already lining up along the parade route, so if you're planning on joining the celebration, stop reading this post and head out the door. The latest update from the City of Seattle Emergency Operations Center is available here. But the gist of it is, dress warm and expect delays!