Most of the time, you get hypothermia after going outside in the cold weather or being wet in the cold air, according to the CDC. It doesn't have to be freezing outside to get hypothermia; in some cases, people get it when it's almost balmy. Shivering is the first sign that someone has hypothermia. When you're in the cold, your muscles contract and relax rapidly (aka shiver) in an effort to make heat and increase your core body temperature, according to MedlinePlus. You might also get tired, because it takes a lot of energy to make up for the lost heat. Confusion, fumbling hands, memory loss, and slurred speech are some other symptoms of hypothermia to be on the lookout for, according to the CDC.