Severe weather has caused significant damage to parts of the rail network in the lower North Island and the West Coast, KiwiRail says.
It said lines were affected by numerous slips, washouts and surface flooding and restoring rail operations in the affected areas was a high priority.
The line between Palmerston North and Pahiatua was expected to reopen late tomorrow and the line between Woodville and Napier late on Friday.
KiwiRail also expected the section of line between Marton and Whanganui to reopen tomorrow.
On the West Coast the Stillwater Line has reopened but the line between Greymouth and Hokitika is still being repaired; it is expected to reopen later this week.