I've only had chickens for a few years now, but after buying my first five at the feed store, I quickly bought an incubator and started hatching my own. I bought the first five in January and the next groups that I hatched out were in the winter. This year I've had about 6 hatches from march to september. I have had the worst luck keeping them alive. The heat is really hard on them. I can keep a chick warm no problem, but keeping them cool in texas after they are a few weeks old is hard. Also predators likes snakes are not hibernating. I've lost chicks and ducks up to six and 8 weeks of age to snakes that can get inside anything it seems. Mosquitos are worse and virus like dry pox that is carried by mosquitos. Any way just wanted to share an opinion that I have come to from my experience of hatching in winter instead of summer. I'd love to hear yours.