"High levels of staff absences due to Covid-19 (over 80 per cent) has required the rescheduling of works which means construction will now finish in June. "
Wellington City Council head of property Peter Brennan said a scaffolding team was struck down with Covid-19.
"It meant that one of the more technical teams was unable to do their work, so that pushed the programme out by several weeks."
But Brennan said the construction work has now been finished and the focus has moved to the commissioning of the theatre.
That involved things like reinstating the heritage finishes, putting the flooring down, and putting the theatre rigging systems back up, he said.
The council will continue to work closely with WellingtonNZ, which manages the theatre and bookings, and the Royal New Zealand Ballet, which is the key tenant.
The Royal New Zealand Ballet will be refurbishing its dance studios and tenancy space once the building works are complete in June.
The strengthening project hasn't been an easy ride.
Last year the council's quarterly reporting signalled the construction completion date for the theatre was "continuing to slip".
"Issues being managed include largely due to seismic gaps, water leaks, resource availability, agreeing pricing, and design detail," the report said.
The project has also experienced issues with the procurement of various materials from overseas because of Covid-19-related shipping delays.