The remnants of Tropical Cyclone Winston are expected to end up in the Tasman Sea at the end of the week.

WeatherWatch analyst Philip Duncan said it will possibly affect New Zealand over the weekend.

"So at this stage the main effect form Winston will be dangerous beach conditions around the upper North Island because this storm is generating swells or peak wave heights of 13 metres."

Mr Duncan said we'll have to wait a couple more days to lock in exactly where the centre of the low will end up going.

It's now halfway between Vanuatu and Fiji, near where it was ten days ago.

Mr Duncan said Winston is generating peak swells of 13 metres.

He said the storm has been trying to get to the South Pole but has been blocked by high pressure in the New Zealand area.

"It's acting a bit like a pinball, it's just bouncing around from one island to the next, waiting for a gap in high pressure around New Zealand so it can drop south."

Mr Duncan said the first window of opportunity for that to happen will be at some stage either this weekend or early next week.