Swells of up to two metres high are set to hammer Hawke's Bay shores on Sunday and Monday.
Niwa Meteorologist Ben Noll said a "tropical disturbance" currently hovering above Tonga is set to pass by the east coast of New Zealand on Sunday with swells peaking by Monday morning.
Luckily the Mega Fish competition wraps up on Saturday as swells could reach up to 1.6-2m with Noll advising those who were out on boats on Sunday to take care.
"On Sunday afternoon through to Monday afternoon the weather seems to come with some enhanced wave and swell action," Noll said.
"It's not a cyclone, but a tropical disturbance which will drop down south from Tonga towards the east of New Zealand.