An Abbotsford police officer holds an infant found left with a two-year-old sibling in a hot, parked van on Aug. 1. (CBC)

An Abbotsford, B.C., father who left his two young children in a parked van in the midst of an August heat wave will not be charged.

Police found a four-month-old baby and a two-year-old in the van in a parking lot at an Abbotsford summer fair the night of Aug. 1. They said at the time the children were in extreme distress, with soiled diapers. The children were taken to hospital and treated for dehydration.

Abbotsford police will not be recommending charges against the 26- year-old father, because they were not able to establish how long the children were in the vehicle, according to Const. Ian MacDonald.

"Without that key piece of evidence, namely, how long the kids were specifically left alone in the vehicle, we would not have a substantial likelihood of conviction," MacDonald said Monday.

After the children were found by police, the Ministry of Children and Families placed them in the temporary care of other family members, MacDonald said.

Police were called to the scene by a woman who overheard the father at a beer garden at the fair saying he'd left the children in the vehicle.

"The wellbeing of the children is still the paramount concern, and the information that I have is that the ministry is still continuing to supervise the children," MacDonald said.

The seven-week investigation and witness interviews simply did not provide sufficient information to warrant charges, according to MacDonald.

Names have not been released to protect the identities of the children.