This occurs because of increased blood flow to hands. Eskimos have increased blood flow to hands which allows them to maintain dexterity at temperatures below those for Europeans. The same effects have been found with Arctic and Northern fishermen. Using hands in cold can affect manual dexterity by decreasing flexibility of digits and decreasing sensitivity. At a critical temperature of fingers at 6 C, there is a dramatic decrease in sensitivity as fingers become numb.
Air speed is an important contributor to cooling of skin temperature.
WCI effectively expresses rate of cooling of skin. Gloves - can substantially protect fingers from wind chilling and cold, although dexterity may be decreased.