Work continues at Our Lady of Fatima school on Sidney Street in Belleville.
There are environmental concerns for the property which is beside the site of the former Nortel building.
Contaminants were found in the soil, so students were moved to George Vanier schoool.
Plans were to have them back to Fatima for mid-October, however, officials with the Catholic board say that will not happen.
Students will not return until after the Christmas break.
Portables, a parking expansion and other infrastructure upgrades took place over the summer at George Vanier, to accept the extra students for the fall.