The Facts on Hypothermia and Cold Weather

Cold water (less than 70° F) can lower your body temperature, causing hypothermia. If your body temperature drops too low, you may pass out and then drown. The human body cools 25 times faster in cold water than it does in air.

Water temperature, body size, body fat percentage and movement in the water each play a part in cold-water survival. Small people cool faster than large people; children cool faster than adults.

Lifejackets can help you survive cold water. They let you float without using energy while insulating your body from cold water. A snug-fitting lifejacket is better than a loose-fitting one. When you boat in cold water, use a flotation coat or flotation coverall. In cold water these are preferred to vests as they cover more of your body and help maintain your core body temperature.

How hypothermia affects most adults


Water Temperature (Fahrenheit) Exhaustion or Unconsciousness Expected Time of Survival
32.5 degrees Under 15 minutes Under 15 to 45 minutes
32.5 to 40 degrees 15 to 30 minutes 30 to 90 minutes
40 to 50 degrees 30 to 60 minutes 1 to 3 hours
50 to 60 degrees 1 to 2 hours 1 to 6 hours
60 to 70 degrees 2 to 7 hours 2 to 4 hours
70 to 80 degrees 2 to 12 hours 3 hours to indefinite
Over 80 degrees Indefinite Indefinite