An icy blast will move its way northwards from today

MetService advises the cold front will drop one to four centimetres of snow on South Island's alpine passes from today, with temperatures to fall at lower elevations.

Meteorologist Alwyn Bakker says people will have to rug up as the front heads north.

He says the southerly blast should clear the country by midnight tomorrow.

Snow is expected to fall to 800 metres in the south.