Road closures meant Fonterra milk tankers were unable to reach about 1700 dairy farms in snow-bound areas of the South Island on Monday.
Lower South Island operations manager Keith Mason says that given the forecast, it's unclear when tankers will be able to reach those farms.
It's possible there will be no collections in Southland until Wednesday.
However, he says that with calving still in process, not all cows are milking and most farmers have capacity in their storage vats to hold the milk if there are delays in collection.
Mr Mason says it's the third time in 12 months that snow has had that sort of impact on Fonterra's operations in the South Island.
South Island tanker drivers stayed off the roads until after 10am on Tuesday, but collection is expected to improve later in the day.
Tanker movements in the North Island are restricted in parts of Wairarapa and Hawke's Bay.
Fonterra is still collating information on the number of farmers affected on Tuesday.