Just about every beach in Auckland is deemed unsafe for swimming today after Friday’s heavy rain washed sewage - including human faeces - into the ocean. 

The Safeswim website warns most of the beaches around the Waitematā Harbour are likely to have faecal levels that exceed health guidelines, with 22 of the most popular beaches bearing a black flag - the highest risk for swimming. 

Mission Bay, Kohimarama, St Heliers and Okahu are all black-flagged as are the North Shore’s Takapuna Beach, Narrow Neck and Torpedo Bay. 

Just four beaches on the Waitematā Harbour in mainland Auckland are safe for swimming today after Friday's downpours, the Safeswim website shows. 

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

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

There are also dozens of red-flagged beaches, such as Maraetai, Pt Chevalier and Cheltenham Beach, where swimming is high-risk and not advised. 

Pt Chevalier Beach is a popular swimming spot but don't go in the water there today - it's red-flagged, meaning it's probably contaminated. File photo / Alex Burton 

“Safeswim water quality models predict that levels of Faecal Indicator Bacteria breach national guidelines for swimming, based on guidance published by the Ministry of Health and Ministry for the Environment,” red-flagged beaches say. 

That’s unfortunate for Auckland-dwellers who will be dealing with a forecast high of 26C today, with bright, dry conditions this afternoon perfect for swimming. 

It poured with rain for most of Friday, and on Sunday afternoon - New Year’s Eve - the rain is expected to start again. 

Those who are desperate for a dip at the beach today have a small list of safe spots where they shouldn’t get sick. 

Devonport Beach, Lake Pupuke in Takapuna and Island Bay near Beachhaven are deemed safe to swim, as is Cornwallis Beach near Huia. 

On Waiheke Island, Palm Beach and Onetangi are both safe for swimming but Oneroa and Sandy Bay are both red-flagged. 

The full list of beaches is available on the Safeswim website. 

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. 

Auckland's Piha Beach is one of the few clean swimming spots today, but swimmers should follow the instructions of lifeguards and stay between the flags. Photo / Alex Burton 

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

Today has dawned humid and hot for much of the North Island and parts of the South. Nelson was set to be the hottest spot in the country today with a forecast high of 32C. 

- NZ Herald