It is very difficult to assess your baby's body temperature. There's a good rule to follow when dressing a newborn or infant that cannot tell you they're too hot or to cold. First, always have them wear one more layer than you. If you're comfortable in jeans and a t-shirt, then have them wear pants, a onesie and a light sweater or blanket. Then if you're still unsure, say at night time when the sun goes down, you can always feel a baby's actual temperature easier by feeling the back of their neck. It is the most accurate spot.