Hypothermia Chart

Hypothermia Chart
Water Temp (degrees) Hypothermia Index Exhaustion or Unconciousness Expected Survival Time
20 to 32 degrees EXTREME Under 7 minutes Under 7-22 minutes
32.5 degrees EXTREME Under 15 minutes Under 15-45 minutes
32.5 to 40 degrees SEVERE 15 to 30 minutes 30 to 90 minutes
40 to 50 degrees HIGH 30 to 60 minutes 1 to 3 hours
50 to 60 degrees CAUTION 1 to 2 hours 1 to 6 hours
60 to 70 degrees MEDIUM 2 to 7 hours 2 to 40 hours
70 to 80 degrees LOW 3 to 12 hours 3 hours to indefinite
Over 80 degrees NONE Indefinite Indefinite

The range 20-32 degrees is not on any official chart as most government sources do not track water temperatures that can reach the very cold conditions that Great Salt Lake can reach.

(source: http://www.gslmarina.com/HypothermiaChart/tabid/82/Default.aspx)


Hypothermia Chart
32.5 Under 15 Minutes Under 15 – 45 Minutes
32.5 – 40.0 15 – 30 Minutes 30 – 90 Minutes
40.0 – 50.0 30 – 60 Minutes 1 – 3 Hours
50.0 – 60.0 1 -2 Hours 1 – 6 Hours
60.0 – 70.0 2 – 7 Hours 2 – 40 Hours
70.0 – 80.0 3 – 12 Hours 3 Hours – Indefinitely
OVER 80.0 Indefinitely Indefinitely

The use of an Immersion Suit or other buoyant thermal protective device will greatly enhance survival time.
Chart is for general reference only.

How cold is my water?

Hypothermia Facts

  • Body thermal conductivity in water is 26 times faster than when exposed to air. If you have a life raft, board as soon as possible.
  • 50 degree water equals 15 minutes before incapacity and/or unconsciousness with life jacket on.
  • 50 degree water equals 9 minutes before incapacity and/or unconsciousness without a life jacket.

Chart and facts courtesy of Winslow Life Raft Company

How cold is my water?

How to Combat Hypothermia

Keeping your body out of the water is the most effective means. Life rafts are everyone’s first choice since they keep you out of the water, provide shelter along with equipment. If you are not going offshore immersion suits are your next best choice. While they do not get your body out of the water, immersion suits provide excellent thermal insulation.

If dedicated life saving equipment is not in your budget figure out ahead of time what you are going to do. A dinghy is an alternative providing it can be quickly launched. If you always travel with another vessel good communications can get help there quicker. At times even items like plastic coolers become the only survival aid available although in cold waters they would not be much help.

(source: http://westpacmarine.com/samples/hypothermia_chart.asp)

Boat Safe this Spring or Fall – Avoid Hypothermia

Even when the weather is warm, do not forget that in many areas the water can be very, very cold. A sudden unexpected wake or other “unbalancing event” can land you in the frigid water. Although the possibility of drowning from falling into the water is a real threat, so too is hypothermia.

Hypothermia is a condition that exists when the body’s temperature drops below ninety-five degrees. This can be caused by exposure to water or air. The loss of body heat results in loss of dexterity, loss of consciousness, and eventually loss of life. A few minutes in cold water makes it very difficult to swim, even to keep yourself afloat. In addition, a sudden, unexpected entry into cold water may cause a reflexive “gasp” allowing water to enter the lungs. Drowning can be almost instantaneous.

Your body can cool down 25 times faster in cold water than in air. If you examine the chart below you will see that survival time can be as short as 15 minutes. Water temperature, body size, amount of body fat, and movement in the water all play a part in cold water survival. Small people cool faster than large people and children cool faster than adults.

PFDs can help you stay alive longer in cold water. You can float without using energy and they cover part of your body thereby providing some protection from the cold water. When boating in cold water you should consider using a flotation coat or deck-suit style PFD. They cover more of your body and provide even more protection.

Hypothermia does not only occur in extremely cold water. It can, and does, occur even in the warmer waters of Florida and the Bahamas.

Hypothermia Chart

If the Water
Temp. (F) is:

Exhaustion or

Expected Time
of Survival is:


Under 15 min.

Under 15 – 45 min.

32.5 – 40

15 – 30 min.

30 – 90 min

40 – 50

30 – 60 min.

1 – 3 hours

50 – 60

1 – 2 hours

1 – 6 hours

60 – 70

2 – 7 hours

2 – 40 hours

70 – 80

3 – 12 hours

3 – Indefinite

Over 80




Hypothermia is progressive – the body passes through several stages before an individual lapses into an unconscious state. The extent of a person’s hypothermia can be determined from the following:

1. Mild Hypothermia – the person feels cold, has violent shivering and slurred speech.

2. Medium Hypothermia – the person has a certain loss of muscle control, drowsiness, incoherence, stupor and exhaustion.

3. Severe Hypothermia – the person collapses and is unconscious and shows signs of respiratory distress and/or cardiac arrest probably leading to death.

Conservation of heat is the foremost objective for a person in the water. To accomplish this, limit body movement. Don’t swim unless you can reach a nearby boat or floating object. Swimming lowers your body temperature and even good swimmers can drown in cold water.

If you can pull yourself partially out of the water – do so. The more of your body that is out of the water (on top of an over-turned boat or anything that floats), the less heat you will lose. Especially keep your head out of the water if at all possible – this will lessen heat loss and increase survival time.

Wearing a PFD in the water is a key to survival. A PFD allows you float with a minimum of energy expended and allows you to assume the heat escape lessening position – H. E. L. P.

This position, commonly referred to as the fetal position, permits you to float effortlessly and protect those areas most susceptible to heat loss including the armpits, sides of the chest, groin, and the back of the knees. If you find yourself in the water with others, you should huddle as a group to help lessen heat loss.

Treatment of hypothermia can be accomplished by gradually raising the body temperature back to normal. Re-establishing body temperature can be as simple as sharing a sleeping bag or blanket with another individual, or applying warm moist towels to the individual’s neck, sides of chest and groin. Remove wet clothes as they inhibit heat retention. A warm bath could be used for mild to medium hypothermia, gradually increasing the temperature. Keep arms and legs out of the water and do not attempt to raise the body temperature too quickly.

Do not massage the victim’s arms and legs. Massage will cause the circulatory system to take cold blood from the surface into the body’s core, resulting in further temperature drop. Do not give alcohol, which causes loss of body heat, or coffee and tea which are stimulants (and cause vasodilation) and may have the same effect as massage.

(source: http://www.boatsafe.com/nauticalknowhow/hypothermia.htm)