April 20th will not feature its usual celebration at San Francisco's Hippie Hill as the annual gathering has been canceled due to public health concerns related to Coronavirus.
The gathering most recently featured between 13,000 & 14,000 people in 2019 when 4/20 fell on a Saturday. It does not appear as if something official will be held at a later date, but they did say "see you next year".
Golden Gate Park remains open to the public so it's likely people will still gather to celebrate the day. Hopefully, while remaining at least six feet apart.