Several of Sydney's beaches were deserted on Wednesday after storms caused major pollution across the eastern suburbs and the northern beaches.

The NSW government has issued warnings about debris and faecal contamination for many parts of Sydney's coast, encouraging members of the public not to go swimming.

North Curl Curl and Tamarama beaches were officially closed due to the likely possibility of pollution and dangerous surf conditions, while warnings to avoid swimming were issued for many other popular beaches, including Manly, Collaroy, Bondi, Bronte and Coogee beach.

Only 4 out of 62 beaches in the Sydney and Pittwater regions were reported to have no pollution in the water.