Some 45,000 people are expected to crowd Gas Works Park on Thursday night to watch the fireworks show. Amid the festivities, the feds have issued a security warning.
The FBI and the Department of Homeland Security sent out a bulletin to local law enforcement pointing out that big celebrations are potentially attractive terrorist targets.
In response, Seattle police will patrol Gas Works Park with uniformed and undercover officers.
Meanwhile, Tacoma is gearing up for Freedom Fair with a police presence. And in Bellevue, police say they've heightened planning to make sure celebrations stay safe.
Melissa Jurcan, Seafair marketing director, says there will be restrictions on what people can bring to the fireworks show.
"You can't bring alcoholic beverages, personal barbecues. We don't allow pets, unfortunately, and any weapons," she says.
Security at Wednesday night's Seattle Sounders game could be a foretaste of what's to come. Some Sounders fans were in line for 40 minutes outside Century Link Field. The team later apologized for the delays.
Jurcan said there will be some other differences at this year's Gas Works Park fireworks show, now that Seafair has taken over organization of the event from longtime producer One Reel.
The Seafair Pirates, Seafair royalty and other familiar Seafair elements will be added to the festivities, Jurcan said.
But one icon of previous shows will not be there. The inflatable Lady Liberty head that has represented freedom on the top of Kite Hill will take a break from her annual appearance. Organizers hope she can return next year.