With a heavy base layer and a primaloft vest, I’d say around 40 for a few hours in a stand with no wind. Add a down jacket or insulating layer with heat warmers, maybe a little lower. Any colder, I’d imagine you would want to go with something else as an outer layer and reduce the middle layers. This jacket probably wouldn’t serve any purpose at that point. Might also be cumbersome to lug all that into the woods and hard to shoot if you’re using a compound.
I don't think you should have any issue. I don't have this one, but I use a keni jacket with a kutana rain shell and a strong fleece 280. That will be okay 32-40. The keni isn't warm unless you are able to block the wind. It doesn't allow you to over heat walking in. If you throw a super down vest under this coat with a 280 or something, you'd be fine in the sun to 30. I use my stuff all the time on the farm, not just hunting. Get to know your cold tolerance. Wind changes the game. I love the kuiu stuff, and it is top notch. But if money is an issue, look at kryptek. They had an ares down coat for 165 bucks on sale because they Discontinued the color. They do put on good deals. That coat is a little less warm than the super down pro from kuiu, but it's also half the price. Years ago I got a cadog fleece coat like this but not wind resistant or this high quality, but it worked. Still use it with kuiu ultra vest.
