Auckland motorists travelling on low lying sections of the city's motorway network tonight are being warned to beware of flooding due to a king tide and strong winds.
NZ Transport Agency acting highways manager Steve Mutton advised motorists to exercise extreme caution.
"We will do everything we can to keep motorways open, but they will be closed and traffic diverted if there is a risk to the safety of road users."
Areas at risk from flooding included the causeway on the Northwestern Motorway (State Highway 16) and the Northern Motorway (SH1) approaches to the Auckland Harbour Bridge.
High tide in the Waitemata Harbour is due to occur at 10.09pm.
The tide was expected to peak half a metre higher than normal, a tidal situation that would be aggravated by strong northerly winds, Mr Mutton said.
"Usually with a king tide, the Northwestern cycleway floods but the situation could be made worse tonight by the impact of strong wind from the north on the height of the waves.
"We will use our electronic signs on the motorways to keep people informed about driving conditions, but we would advise them to either avoid travel when the tide peaks around ten o'clock or to take extreme care if they do have to be on the roads."
Local roads in many coastal areas of Auckland will also be affected by the tides and wind, Mr Mutton said.
The MetService has also warned that a storm bringing northerly winds to Auckland, combined with the king tides was likely to cause localised coastal flooding.
Auckland Civil Defence expected that waves would affect Tamaki Drive and low lying properties at Kohimarama and Maraetai.
"If you live in an area where there is a possibility of flooding the best thing to do is to take preventative measures now to protect your home," Auckland Civil Defence Controller Clive Manley said.
Auckland residents can receive emergency warnings on their smartphone by downloading the free Auckland Civil Defence smartphone app here.
Areas likely to be affected
* Stanmore Bay, Whangaparaoa
* Big Manley, Whangaparaoa
* Mission Bay and St Heliers Reserves
* Bucklands Beach
* Kawakawa Bay
* The Strand, Onetangi Waiheke Island