MetSerice said the front would be preceded by north to northwest gales and was on track to move across the South Island from Wednesday through to Friday.
The forecaster has issued a raft of severe weather alerts for much of the South Island.
These include an orange heavy rain warning for the headwaters of the Otago lakes and rivers, from midday tomorrow to 6am on Thursday.
MetService said surface flooding, slips, and difficult driving conditions were possible. It urged people to clear drains and gutters.
There is also a strong wind watch in place for the Queenstown Lakes District, Central Otago and Southland about and north of Lumsden, from midday tomorrow through to 3am on Thursday.
MetService said north to northwest winds could approach severe gale in exposed places.
