Emergency crews had to use an aerial platform to fight the blaze, in which no-one was injured.
The latest update from Plymouth City Council is that the repair work to the building may not be finished until the end of March, meaning services may not resume until April.
Staff from the crematorium on Efford Road say they are working extra hours trying to accommodate extra services at Weston Mill.
The full update from Plymouth City Council:
The Council has stressed the plans may change once a full investigation has been carried out.