In sg, I don't think it is necessary as the weather is humid and warm here. It also depends if your baby likes to have anything on the head.
Yes, it helps to regulate the baby's temperature. You can google for more information.
Not important. My infant have never like to wear hats. Bought alot end up never use.
my girl didn't wear hat after discharge from hospital cause she has alot of hair.
Good to have if your are in an air-conditioned environment
My girl didn’t wear hat since she left the hospital.
my girl didn't wear. she hates it