Replying to Under my shell...

should i wear anything heavy considering its not insulated or anything, or doesnt have anything heavy in insulation? would i be able to get away with just a long sleeve shirt in like 15 degree(fahrenheit) weather? or would i need to wear a t shirt, long underwear on top, and a sweater... sorry if this is stupid, if you have a problem with this thread then leave i just need a straight answer. and same with pants. would long underwear and thats it be okay?