Wellington, March 20 NZPA - A frontal system is expected to bring heavy rain to Fiordland and Westland and northwest gales to parts of Otago and Canterbury on Monday morning.

Metservice forecaster Chris Noble said the heavy rain was likely to create a "spillover" effect at many South Island lakes and rivers and people needed to keep up to date with forecasts.

Eastern Otago, north of Dunedin, and inland parts of Canterbury are expected to be hardest hit by the winds.