Waves up to seven metres high are set to batter the Rena this weekend while the state of the stranded ship remains uncertain.
The ship is now effectively in two pieces, but is still stuck on Astrolabe Reef off Tauranga where it has been for three months and may be still joined underneath.
Maritime New Zealand (MNZ) describes the ship's condition as "fragile but stable" and says this weekend's forecast is one of the worst yet.
A low pressure system is expected to arrive on Saturday afternoon, with the worst of the weather to hit on Sunday.
MNZ said teams were on standby to deal with any potential oil spill caused by the bad weather.
At a media conference today MNZ national on-scene commander Alex van Wijngaarden said that if the ship breaks in half "we'll have to deal with that as it happens".
Van Wijngaarden said that MNZ "remain ready to respond if something is released from an oil spill perspective, but we just have to wait and see, that's all we can do".
Salvors would be trying to make the most of the good weather expected for today and tomorrow to remove containers.
Fourteen containers were removed from the wreck yesterday and salvors will try to move more today. Around 898 containers remain onboard.
The remaining containers have been lashed down and tracking devices have been installed should they topple into the sea.
Since the Rena ran aground on October 5, a total of 98 containers have been lost overboard, while 372 have been removed.
Bad weather yesterday stopped divers from inspecting the bottom of the vessel to see the extent of the damage.
Debris, comprising mainly plastic and milk powder, and some meat products, were picked up from Papamoa Beach and Maketu this morning.
MNZ is urging people not to touch container material after clean up teams reported a number of milk powder packets appear to have been opened after arriving on shore.
Van Wijngaarden said oil slicks between ten and 15 metres wide, and up to 5km long, are still forming around the vessel.