Network Rail says it will have to take "a phased approach" to reopening the Cambrian Coast line.
The line is expected to reopen as far as Barmouth by February, but the stretch from Barmouth to Pwllheli will not be fully repaired until May.
"This has been an extremely challenging period, but the rebuilding operation is underway and our priority is to safely re-open the railway as soon as is possible" says Network Rail's Mark Langman.
"I would like to take this opportunity to apologise for the on-going inconvenience and also thank rail passengers for their patience as we repair this unprecedented damage.”
Winds in the area reached speeds of more than 50mph on Saturday night.
Coastal and flood-prone communities across Wales are preparing themselves for another battering from the weather this weekend
Ceredigion Council estimates that damage in Aberystwyth and elsewhere in the country will top £1.5m.