A spokesman for Defence Minister Gerry Brownlee said that the aircraft was flying north from Whenuapai when it developed pressurisation issues and turned back.
Residents near the airbase said the weather was extremely cloudy with limited visibility.
The RNZAF operates five C-130 Hercules. It is a large aircraft capable of carrying up to 92 people, although it is also used for carrying freight.
The New Zealand Hercules fleet has recently been modernised, according to the Air Force website, "to ensure they last until 2015".
The original three Hercules in the fleet arrived in the country in 1965. Another two were acquired in 1969.