As Bob says, you will be warm but take this to consideration.....
While moving around during snowboarding / snowkiting your body creates body heat. When layering up you can take a layer off put it in your back pack and put it back on if needed.
On the hill or mountain: Nothing more then long underwear and my Snowboard pants. A thermal tank top, thermal long sleeve and a fleece shirt and my jacket. This has been my setup on the mountains for at least the last 10 years.
A wetsuit will make this a lot harder to do. Just my thought.
Also keep in mind when in a wetsuit, you'd probably start sweating a lot faster. You need to hydrate..... Wouldn't pee in the suit on the hill! LOL