A warning for South Island motorists as heavy snow could cause disruptions on alpine passes

MetService has issued heavy rain and snow warnings for inland Canterbury and Otago.

Heavy rain is also expected for Tasman west of Motueka and the Richmond and Bryant ranges.

Police and NZTA are urging motorists to be patient and drive at a safe speed, especially around and through road works this weekend.

Meteorologist John Law says there are road snowfall warnings for all the main passes.

He says between 20 to 30 centimetres of snow could fall at the top of Arthur's Pass.