Police Search and Rescue were called in and with the help of the Whangarei and Kawau Coastguards, two IRBs from Mangawhai and Waipu Surf Lifesaving clubs, and the Northland Electricity Rescue Helicopter, they searched for the pair.
At 5.45pm they were spotted by an officer in the helicopter 2.5km offshore, north of the Waipu River mouth. They were still with the jetski and the boy was winched on to the helicopter and the man was picked up by the Whangarei Coastguard.
The father suffered no ill effects from the four-hour ordeal, but the boy had signs of hypothermia.
Mr Metcalfe said it was "sheer stupidity" to go out in the conditions.
"They put their lives and the lives of those rescuing them at risk. Police are very disappointed in their actions and a family nearly lost two of their members just two days before Christmas.
"They are so lucky to have survived this ordeal," he said.
Mr Metcalfe said the weather was so bad the Coastguard Rescue Centre was monitoring marine conditions every 15 minutes to ensure the safety of its crew.
"The trained police officer, who was looking for the jetski from the helicopter, just spotted it as the helicopter was flying past. A boat would probably have never found them in those conditions," Mr Metcalfe said.
Police Search and Rescue Incident Controller Constable Sue Grocott said this was a timely reminder for people to check the marine forecast before heading out on the water and definitely not to venture out in rough sea.
Ms Grocott said after the rescue some other family members went out on another jetski to bring back the one that had been taken out by the rescued pair.
"This action is completely irresponsible, considering two family members had just been rescued from rough sea and were lucky to survive," she said.
"The only saving grace was that the pair had on lifejackets and were wearing surf wetsuits."