In winter everything is much more complicated. If in the summer it is necessary to ensure that the concrete does not dry up, then in cold weather - that it does not freeze (and this is much more difficult). First, special frost-resistant additives are added to the concrete mix, which prevent the water from freezing. Secondly, a kind of tent-greenhouses are organized, the main task of which is to maintain an acceptable temperature.
As you can see, pouring concrete is a very laborious and complex process, requiring careful compliance with a number of rules and regulations. That is why the casting of concrete is best entrusted to professionals who will ensure the most correct order of the work.