Mourning Doves have multiple broods each year. There is very little time when they aren't somewhere in the process of reproducing/rearing. Extremely cold weather may deter them; a steady food supply may accelerate the nest building (such as it is) and egg laying, despite cold weather.
I'm probably going to be sorry that I sent this, because I'm probably way off base. Outside the library window at the school where I teach, there is a Mourning Dove nest. Knowing that I am a bird watcher, one of the other teachers came to me today to tell me about it. She thought it was a pair just beginning to nest. When I went to look, I discovered an adult and two (that I can see) immature doves. The juveniles are feathered and practically grown. I couldn't believe that it was possible on April 10th for things to be that far along. Wouldn't she have had to lay her eggs the first of March or so? Isn't that a little early? I thought nesting season for most passerines had just begun.