More than 20 Auckland beaches remain unsafe for swimming after last Friday’s deluge washed sewage including human faeces into the sea.

However with a sunny New Year’s Eve and warm mid-20Cs weather, many seem to be disregarding warnings and getting into the water.

The Safeswim website has placed black-flag warnings, the highest risk for swimming, on popular beaches including Mission Bay, Kohimarama, Cheltenham, Milford and Mellons Bay.

The wastewater overflow means swimming at these beaches poses a “very high risk of illness”.

More than 20 beaches have been "black-flagged". Photo / SafeSwim

However, just after 9am this morning people could be seen swimming in Mission Bay.

Safeswim is an Auckland Council-led initiative that monitors and predicts the water quality at the city’s beaches.

Dozens of beaches remain red-flagged including Maraetai, Cockle Bay, Eastern Beach, Farm Cove and Te Atatu Beach, where swimming is high-risk and not advised.

“Safeswim is a real-time website, offering beach water quality and safety information, so it’s a great idea to check before you head out to see if there are any issues with water quality at your destination,” a Council spokeswoman said.

Kohimarama Beach has a black flag warning. Photo / Dean Purcell

Although the morning weather has been bright and dry, perfect for swimming, rain is forecast to start again in the afternoon.

Those keen for a dip at the beach before the rain can do it safely at quite a few beaches still.

Browns Bay, Mairangi Bay, Lake Pupuke in Takapuna, Point Chevalier and Bayswater are all deemed safe to swim.

The more dangerous surf beaches on the west coast remain green, including Muriwai and Piha. Swimmers should stay between the flags and follow the instructions of lifeguards, who are on duty from 11am to 5pm.

Karekare Beach is closed to non-residents following damage from Cyclone Gabrielle.