Left Bank is operating out of an undamaged room upstairs, while CES is housed in a UCOL campus building.
Ms Watson said the centre was due to open on September 29 for its first exhibition since the floods.
"The floor won't be polished and the walls will still be in progress, but we will be able to have an exhibition."
Frances Stachl's jewellery workshop, on Moutoa Quay, which was inundated with mud and water during the floods, is now back up and running.
Meanwhile, the Sarjeant On The Quay has decided to move its annual Whanganui Arts Review to early next year because of the floods. The gallery was damaged, with the floor covered in sludge and silt and damaged paint on the wall linings.
All the artworks were safe.
The gallery is set to reopen on September 26.
The arts review has been postponed and will open on March 4. It will run for 12 weeks.