A mosaic of severe weather warnings and watches cover much of the South Island today and tomorrow

Strong winds and heavy rain are travelling up the mainland.

Up to 200 millimetres of rain is expected in the Westland ranges - and 100 millimetres nearer to the coast.

MetService forecaster, Lewis Ferris, says orange heavy rain warnings currently apply for Westland and Fiordland - among other alerts.

He says a heavy rain watch for Southland, including Stewart Island, runs until 3am Tuesday.