Boaties thinking of heading out anywhere on the country's West Coast are being warned to watch out for "rogue waves" of up to 10 metres tall

NIWA says the combination of king tides, churning seas, and heavy swells are likely to produce unusual wave patterns this weekend.

Maritime officer Matt Wood says even if it looks safe from shore, boaties need to check the marine forecast to ensure it's safe to head out.

He says waves can be unpredictable, so skippers need to ensure their vessels are suitable for the conditions.