Wellington's south coast is getting a hammering this morning, with waves of up to nine metres.

MetService duty forecaster William Nete says it's been rough enough to cancel some ferry sailings.

"We've got a wave rider along the south coast there and that's measuring currently six metre waves and occasionally nine."

The Interislander's Cook Strait ferry service is not taking bookings, as weather is expected to disrupt services.

On Saturday afternoon ferries were cancelled for 24 hours but a spokeswoman said there would be a further update later this morning and passengers will be contacted if plans change.

William Nete also expects big waves along the North Island's east coast this morning.