A wet autumn has driven the price of vegetables to an almost six-year high.
Vegetable prices rose 16 percent in May, and 30.9 percent for the year.
"Our wet autumn has pushed vegetable prices to their highest level in almost six years in May, with the largest annual increase to vegetables on record," Statistics New Zealand consumer prices manager Matthew Haigh said.
"The increase was more pronounced because warmer-than-usual weather in the 2016 growing season resulted in cheaper-than-usual vegetable prices in May last year."
Food prices rose 2.4 percent in May, and 3.1 percent for the year.
The rising cost of vegetables was tied to higher prices for lettuce, tomatoes, and broccoli.
Statistics New Zealand said the average price for a 500g head of lettuce was $5.28 last month, compared with $2.12 a year ago.
The president of United Fresh, Jerry Prendergast said the ground was unseasonably saturated in autumn, which adversely affected crops.
"Cyclone Debbie came through near the end of March. Cyclone Cook came through in April, bringing a deluge of rain and weather problems causing havoc to growers like they've never seen before."
"But there's another trick to this. In between that period we had that low pressure which also brought consistent rain."
Fruit prices fell, with lower prices for mandarins and kiwifruit partly offset by more expensive avocados.
Shoppers also paid more for general groceries, particularly cakes and biscuits, while the cost of lamb jumped 16 percent in May.
The average price for a kilo of lamb leg roast was $15.14 in May 2017, compared with $12.57 in April 2017.
On an annual basis, the 3.1 percent increase in food represented the biggest increase since September 2011 - the year after GST increased from 12.5 to 15 percent.