The quake struck at 3.47am, 120km northeast of Whangamatā at a depth of 5km.
On GeoNet, more than 2500 people reported feeling it.
GNS Science seismologist John Ristau told the Herald shallow earthquakes, like the one on Saturday morning, often triggered aftershocks.
"There is a chance of a larger aftershock some people might feel," he said.
"It wouldn't be outside the realm of possibility that there would be an aftershock of about magnitude four or maybe a bit bigger than four."
However, Ristau said it was also possible any aftershocks would be small and no one would even feel them.
Social media was awash with people who claimed to have been woken by the early morning shaking.
Anthony Peters was woken in Clevedon and said "felt like the washing machine was on spin and the house was shaking for about five seconds".
Carla, from Whangamatā, said she and her husband were both woken to a loud noise, and jumped out of bed to investigate.
"I went into my husband's office, some things were off his shelves and on the floor," Carla said.
"We couldn't work it out, I did say must of been an earthquake, not really believing it until this morning's news."
Brian, who was on Waiheke Island, emailed to say he felt mild shaking.
"Knew what it was immediately. First thought was is this the big one hitting Wellington? Just what we need! Then went back to sleep," Brian said.
Glen Eden resident Susan Lucas said she woke up after feeling herself rolling around in the bed: "So bizarre and yet excitingly different sensation."
Karen, from Ararimu, says she owes her 12-year-old son an apology after he came into her bedroom at 3.54am saying his room was shaking.
"I lifted my head off the pillow, couldn't feel or hear anything so told him not to be silly and go back to bed," Karen said.
"He was shaken and couldn't go back to his room so jumped in our bed. Now I read the news this morning I'll have to apologise to him when he wakes up!"
Helen Fewings, from Hikutaia, said her husband felt a jolt and she thought the bed was floating in a swimming pool at the time.
Auckland doesn't usually get rocked by earthquakes and while they are common in the Bay of Plenty, Ristau said they weren't usually as far north as today.
The reason it was felt so strongly across Auckland, despite being some distance away, was simply because of the strength of the quake.
"Last time there was anything of any reasonable size near Auckland was at the beginning of 2019 when there were three magnitude fours," he said.
"Those only had a couple hundred felt reports, not like 2500 that we've had for this one but that's probably due to the magnitude more than anything else."
