This jacket is VERY warm. If it's above 50 degrees you are going to get hot real fast. Below 47 is better. It is windproof and has a thick fleece like lining. The jacket is form fit, so you won't be able to layer up much under it, but you won't need to. I can only get a base layer under it as the sleeves are fairly snug. I ordered this Jacket for the coldest winter days and it's exactly what I needed. So glad I have it. I love the look of this Jacket. I'm 5'2", 120 lbs. A size small is a perfect fit!
Note: if you are a casual rider, you may not heat up as much and be able to wear it in the 50 degree range.
Yesterday the temp was 43 wind chill was 33. I had this jacket and a base layer and I was perfectly warm the whole ride. Very happy.