Depends on how you're comfortable - either you can nurse vertically or else you can adjust so baby is horizontal. AFA heat - the Moby is a t-shirt material so it would basically take the place of a layer, which isn't bad during the winter/spring but can get hot in the summer depending on where you are. There is another alternative called the Hug a Bub, which is the same idea but a cooler fabric - but also more $$.