The chill is setting across the country ahead of winter, with Christchurch facing the prospect of sub-zero temperatures.
MetService said some of the coldest temperatures overnight on Monday were in Tekapo (-3.7C), Dunedin Airport (-2.6), Christchurch (0.8) and Alexandra (-2.2).
It said the first two weeks of May were expected to be on the cooler side due to southwest winds moving up the country.