"They said they were regularly going back to check on her and that they were in shops close by, but the information we had from people who had been there a while was that they couldn't see (the couple) and they hadn't been back at the van for a while.
"This may have been the case but we needed to action anyway."
Mr Thawley said the action taken by police was a precautionary measure to prevent what could have been a bad situation.
"It was one of those cases that was more of a preventative measure than one where the kid was actually hurt.
"We were alerted by a member of the public who saw the baby in the van and rang us. We responded straight away.
"Initially we looked for the parents in the surrounding shops, and they were actually there but they didn't take any notice of us, and after we didn't find them, we smashed the window and got the baby out," he said.
Mr Thawley said the couple were co-operative with police and were told not to leave a baby in a vehicle without any windows open.
The duo were warned but no charges were laid, Mr Thawley said.
The MetService said the temperature in Kaikoura on Wednesday last week was 21.3 degrees at midday and 20.5 degrees at 1pm.