Gov. Gavin Newsom's team visited Disney World weeks before issuing guidelines that have kept California theme parks closed.
On the plus side, per capita revenue, admissions, and in-park spending increased in 2020.
The park will be built on a 4.5-acre parcel of land that is currently part of Legoland's parking lot.
The event will start March 18 and run on select dates through April 5.
The rest of the Grand Californian and Disneyland's other two on-site hotels will remain closed.
The park will be taken over by Herschend Family Entertainment, the company behind Dollywood and Silver Dollar City.
Several parks' reopening dates depend on government COVID-19 guidelines.
Six Flags Magic Mountain and Legoland California both announced new, ride-less events Thursday.