The emergency mobile alert system is being tested between 6pm and 7pm on Sunday.
According to the National Emergency Management Agency, about 90 percent of New Zealanders will either receive the alert or know someone who did.
Emergency Management director John Price said the test would allow officials to check the system is working as it should.
"If you get an alert, you must stop and read the message, and take it seriously. It will tell you what the emergency is and what to do."
No form of technology was completely failsafe, Price reiterated.
"Emergency mobile alert does not replace other alerting channels, like radio or social media, or the need to act on natural warning signs," he said.
"Please act immediately if you feel your life is in danger. Don't wait for an alert, don't wait for an official warning - just get yourself to safety."
Ahead of the test, Price reminded people to be prepared for an emergency.
"If you don't already have an emergency plan, now's the time for a 'prep talk'. Get ready so you and your whānau know what to do when an emergency happens."
Newshub.
