Mid-summer snow is reported to be settling in Porters Pass in Canterbury.
Snow was falling in the 945m altitude pass, which runs between Springfield, west of Christchurch, and Arthur's Pass, on Sunday, Weather Watch says.
Arthur's Pass is also experiencing hail and wintry conditions.
Traffic is heavier than usual and the conditions are "completely winter-like", Andy Thompson of Weather Watch says.
It expects the current cold snap to pass by Tuesday.
Southern police communications say no issues have been reported.
NZN