The amount is less than the $103 penalty allowed for by Washington's legal marijuana law, and it's equal to the fine in Seattle for drinking in public.
The legislation adopted Monday calls for police to first issue a warning, when practical, and it requires the Seattle Police Department to monitor enforcement by age, race, sex and location, so that the council can evaluate whether the law is being fairly enforced.
While smoking in public had never been legal, police officers took a hands-off approach to enforcing the law.
"For 2013, what you saw a lot of was public education for marijuana legalization. Enforcement was not what we were focusing on," said Det. Sgt. Sean Whitcomb.
Monday's vote signals an end to the grace period for smoking in public.
"We're not afraid to cite," Whitcomb said. "And with this ordinance, I think people should look for more enforcement."
The measure would take effect 30 days after being signed by the mayor. A spokesman for Mayor Mike McGinn did not immediately return a message seeking comment Monday.