The 4-month-old baby found dead in Waiuku yesterday was sleeping with her mother in a van.
They were sleeping in the vehicle as their house was being renovated.
But a post-mortem examination this morning was inconclusive as to the cause of death.
Police are looking into whether the temperature inside the vehicle could have contributed to the baby girl's death.
MetService meteorologist Tom Adams said temperatures at Auckland Airport reached a high of 20.6C at 3pm. He said the temperature in Waiuku would have been similar.