The perception of cold, like that of pain, is absolutely an individual one. What is comfortable to many, if not most people, may be unbearably uncomfortable to others. A large number of medical, genetic, and/or environmental conditions affect these things---too many to list or even try to identify.

The only solution is to try to gauge the individual's own susceptibility to the precautions and equipment in your planning.

As an example, I tend to wear a sweater and/or long sleeves when many around me are in short sleeves. . . .I am one of those who need those "warmer" sleeping bags.