The closure also affects boat ramps, athletic fields, and public golf courses, according to Seattle Parks.
Everything was expected to reopen Tuesday morning, but the closures were extended due to the poor air quality.
People who go to Seattle parks despite the closures will not be cited. The city said it would instead focus on educating them and urging them to stay home.
Additionally, the city and King County are opening emergency shelters for homeless people at the greatest risk.
City and county officials said they've been weighing the hazard of wildfire smoke with the hazard of the coronavirus all week. The hazard of the spread of coronavirus outweighed the hazard of the smoke until Friday when air quality degraded, they said.
Air quality on Tuesday is expected to remain “unhealthy” and “very unhealthy” for everyone for much of the Puget Sound region. Seattle Parks said all residents are “strongly encouraged” to remain inside and avoid outdoor activities until the air quality improves.
The smoke is expected to gradually diminish this week with improving air quality as cleaner air finally begins to move in from the Pacific.