A frontal system working its way slowly on to the south and west of the South Island later today will bring some heavy rain to Fiordland and up to about the glaciers by Friday morning.

Up to 150mm could fall by 6am tomorrow in the Fiordland mountains, with 30mm to 50mm by the same time further north.

This front in a mild northwesterly flow is expected to stall on Friday morning over the south of the South Island and then weaken during the afternoon, with rain on the West Coast slowly easing.

North of about Balclutha, and right up the South Island’s east coast and across Nelson and Marlborough, Thursday will be a dry day and becoming mild.

The North Island too will be dry, with the possible exception of a few specks of drizzle about the Wellington hills in a strengthening northerly flow.

For rainfall accumulation maps for 1, 2 and 3 days out please visit our new maps page: https://www.weatherwatch.co.nz/maps-radars/rain/accumulative-rainfall

By Guest Weather Analyst Paul Gorman – WeatherWatch.co.nz