The temblor struck at about 6:52 p.m. PT, about 38 kilometers northeast of the town of Masterton, according to the United States Geological Survey.
There were no immediate reports of damage or injuries.
The quake was followed by three aftershocks, all magnitude 4.2 or greater.
A giant eagle sculpture in Wellington's airport, placed there to promote director Peter Jackson's movie trilogy "The Hobbit," fell from its overhead perch to the floor.
New Zealand lies on the Pacific's "Ring of Fire," an arc of earthquake of volcanic activity that stretches around the Pacific Rim.
The Associated Press contributed to this report.