Civil Defence will test tsunami sirens in parts of Auckland from midday on Sunday.
The 35 minute exercises are conducted twice yearly, at the beginning and the end of daylight saving.
Sirens to be tested are located at West Auckland beaches and in Rodney.
Civil Defence Controller Clive Manley says three stages of alerts will be sounded.
The first - dash-dash-dot-dot - means a threat of a tsunami, so people should prepare to evacuate.
It will be followed by a continuous dot-dot-dot, which means people should move to higher ground.
Mr Manley says the all clear is a continuous tone.
He says people should act as if it was a real emergency, to see how prepared they really are.
