The news comes after New Zealand declared in December that all areas north of Auckland Harbour Bridge in Northland as well as Waikato and Ruapehu were medium-level drought zones.
In its quarterly dairy report, which also came out in December, agricultural lender Rabobank said it anticipated production of milk would drop between 5% and 15% in the second half of the season.
Arla said it did not envisage any impact on Anchor butter, which is made from milk sourced from New Zealand. "At the moment they're not expecting any issues with regard to volume or price," said a spokesman.
Rabobank has since revised its figure to 5% in view of there being more rainfall than expected.