What are California military child visitation laws? ?

My husband is active duty Army and wants to be able to have visitation with his 2-year son more than on month out of the year. (Without having to go to California to online pharmacy without a prescription stay the whole time) Is it possible for him to be able to see his son in the state of Virginia where we live for a few months out of the year? Tried working it out with the mother but that isn’t going well.