MetService says temperatures in parts of the South Island will plummet on Tuesday, as cold air moves north.
The agency says Christchurch recorded temperatures in the 20s over the weekend, but could get to just 14 on Tuesday, with overnight lows reaching freezing point, leaving a frost.
Meteorologist Daniel Corbett said the cold will continue to the end of the week.
The North Island should stay warmer, but temperatures could fall low enough to leave frost on the Desert Road.
