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.

Meteorologists predict that waves will lessen tomorrow and continue into Saturday. The peak wave period will last up to 18 seconds before gradually decreasing.

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

Despite the strong ocean energy, beaches will remain relatively calm. However, approximately every 10 minutes, exceptionally strong and large waves will crash.

Swimmers and surfers should also be wary of stronger rips.