Huge waves are forecast to batter the NSW coast this week, with boaters, rock fishers, surfers and swimmers warned to stay out the water.

The Bureau of Meteorology has issued a hazardous surf warning for 2500kms of the NSW coast, from Byron Bay to the Eden Coast.

Across these areas, wave heights are forecast to reach a maximum of five metres early today.

The impact of the large surf together with the high tides yesterday and today are expected to cause coastal erosion in some parts of NSW.

From late today, swell heights are expected to decrease to a maximum two metres.

Forecasters say they’ll reduce further tomorrow and into Saturday, while the period of the waves peaking will last up to 18 seconds before slowly shortening.

This will cause waves deep in the Tasman Sea to peak at a staggering 100 metres to 150 metres.

This intense ocean energy will mean on the beaches there will be relatively calm conditions, but about every 10 minutes very powerful and large waves will break.

Swimmers and surfers should also be wary of stronger rips.