International yachties won't be able to seek shelter in New Zealand during cyclone season.

Up to 250 boats are seeking a safe harbour.

Ocean Cruising Club roving Rear Commodore Guy Chester told Mike Hosdkingthey understood two weeks ago that seasonal conditions would be taken into account.

They've since been told refuge from the South Pacific cyclone season isn't a compelling reason, and exemptions won't be granted.

"We're quite dismayed. It leaves a whole lot of yachts at risk in the Pacific cyclone zone, that would normally migrate towards New Zealand and stay around the North Island for the summer."

Foreign yachts waiting to leave the Pacific have been told to make immediate, alternative arrangements.

Chester says the boaties would have a coronavirus test before leaving for New Zealand.

"To have have complete self-isolation on the boats until they arrive, to only the officials onboard for clearance, to then maintain complete self isolation."

He says the club had negotiated a self-isolation process with marinas in Whangarei and the Bay of Islands.