With temperatures expected to reach a bone-chilling high of 27 degrees Thursday, doctors are recommending New Yorkers layer up.

On a day cold enough for people to see their breath, health experts say packing on the clothes can prevent hypothermia and frostbite. People lose up to 40 percent of their body heat through their head, so hats are highly recommended.

"When shivering stops, your body can't compensate," says News 12 contributor Dr. Richard Schutzer. "You start to feel lethargic over time."

Officials also recommend staying clear of alcoholic drinks, saying they suppress shivering and lower the body's natural insulating properties.

The elderly, young and ill are especially at risk for hypothermia and frostbite, according to experts.