It's blood pressure.
Our bodies adapt to the cold conditions by changing our blood pressure to keep us warmer in winter months. It drops in summer to lower levels.
Some people who have naturally high blood pressure don't get the benefit of increased blood pressure they just die of some cardiovascular problem (stroke, heart attack, aneurysm etc)
But I'm as white as they come and had mild frostbite several times, face, fingers, toes and etc. Skin comes right off. If I stayed outside longer I would have lost more than skin. It starts destroying muscle tissues and blood vessels...that's when it begins to be very dangerous.....not all tissues come back and infection can set in. Meaning amputation.