Westland and Buller are being warned of possible tornadoes and could be lashed by gale force winds of up to 110km an hour, according to MetService.

MetService forecaster Mark Pascoe said a cold front is moving across the South Island today and is likely to bring a burst of heavy rain and westerly gales.

He said 90mm could fall in some parts of Fiordland and some areas could get 15mm in the space of an hour.

In the east, gale force winds of up to 110km an hour are expected in some areas of Canterbury and Central Otago.

Mr Pascoe said further north, the gale force winds could reach the Tararua District and the Hawkes Bay tomorrow.

He said northwesterly winds are also expected to rise to gale-force in exposed places, with gusts 100 km/h or more in Marlborough and Wairarapa this afternoon.