A sweatshirt? If it's really that warm I've been known to ski in jeans, bout that Max Hill life. But less layers. Even on cold days, I usually just wear a t-shirt, crew, and my jacket.
i like crewnecks for really warm weather (saga one from like 5 years ago), or a saga foundation hoodie, or a saga shutout or my old first drop jacket with the sleeves zipped off