One significant difference I am aware of in fall versus spring or summer is the food, depending in how much comes from forage versus what you buy or feed them. My garden is not producing in the winter months so they don’t get the extras from that. General forage is not as good. I wind up buying more of their food if I raise them during the winter.
Cold is not much of a worry for me. I don’t know your climate but the broody should not wean them until they can handle the cold. With them being raised outside they will be acclimated and should be fully feathered by about 4 weeks and able to take pretty severe cold.
One potential problem, again depending somewhat on your climate, is providing enough space for them. If you let the broody raise them with the flock instead of isolating the broody and chicks, the chicks will be integrated when she weans them. But they will be at the bottom of the pecking order until they mature enough to establish themselves in the pecking order. If they have enough space they will avoid the older ones and life will be good. But if your space is tight you can easily have problems any time of the year. If your winter weather restricts their space where they cannot avoid the older chickens you might have problems then. How much room you have and how your winter weather affects that could have an impact. If you isolate the broody and chicks form the flock, you have to face an integration at some point. Integration goes better if you have more space. I don’t know what impact your winter weather may have on space available.
Again depending on your weather, they might spend more time indoors than they would in better weather. You may be managing more poop than normal.
When you have different aged chickens in the flock it is often a good idea to have separate feeding and water stations. That way the older ones have more trouble bullying the and not letting them eat and drink. Not knowing how much room you have, how it is configured, or how the winter weather might affect that where you are, I don’t know what kind of impact that may have with you.
When you hatch you will likely get males and females. I don’t know your plans for any males, but if they go through puberty in late winter, the space they have may be limited due to your winter weather. Cockerels going through puberty can make life real exciting in the flock. If space is limited the potential for injury goes up. If you have a bachelor pen for them you can reduce the chances for a problem greatly by housing the cockerels separate from the rest of the flock.