The newborn girl was found in a bus shelter near the Magpie and Stump pub in Towyn, Conwy County at 7:15am.
She is receiving treatment at Ysbyty Glan Clwyd in Bodelwyddan, Denbighshire.
Daniel Braxton, who found the baby, said he wrapped it in a dressing gown he had in his car.
A local resident said she heard a police helicopter early this morning.
Police say they are concerned about the welfare of the baby's mother and have urged her to come forward.
The baby girl was found at around 7:15am Credit: ITV NewsChildren's charity the NSPCC have also urged the mum to come forward.
