A strong wind warning has been issued for this weekend, across most of the South Island and the lower North Island.

For most of Otago, excluding Clutha, northwest winds may approach severe gales in exposed places from 11am on Saturday to 1am Sunday (September 16-17), Metservice reports.

A strong west to northwest flow becomes established over the country on Saturday and continues into early next week.

The wind is predicted to hit Clutha and Southland at about 9am on Saturday, and move away by 11pm, while the Canterbury Plains could be battered for much longer, from about 6am Saturday to 9pm Sunday.

Fast-moving embedded fronts bring bursts of heavy rain to western parts of the South Island, with significant spillover into the Canterbury and Otago headwaters. 

Gale or severe gale northwesterlies are expected to affect many areas in central and southern New Zealand.