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Winter cold fills the air.  Water temperatures plummet.  Clouds block the warming sun and the winds chill you to the bones.  But the surf is really good!  This is the time to protect yourself because cold kills.

Knowing what the condition is, recognizing it, treating it and preventing it in the first place are important!

What is Hypothermia?
Hypothermia is a lowering of the core temperature of your body.  Normal body temperature is 98.6oF (37oC).   When your body temperature drops too low (86oF, 30oC), you lose consciousness.  Cold water reduces body heat 25-30 times faster than air and, when you're in the water, your "core" (brain, spinal cord, heart and lungs) temperature drops.

Charlie Cruz suited up and ready for dawn patrol.  He's fully protected with hood, booties, gloves and a full wet suit.

According to Alaska Information Cache, "The rate of body heat loss depends on water temperature, the protective clothing worn, percent body fat and other physical factors, and most importantly the way you conduct yourself in the water."

Cold kills in two steps: exposure and exhaustion.  The colder the water, the less time you can survive (see Chart A).

How do you know if you or something with you has it?

One of the key signs of early hypothermia is shivering.  If you start to shiver, if your teeth start chattering, get out of the water and warm up!  If you see someone with those symptoms, tell them to go get warm.  

Other signs of hypothermia include loss of coordination, mental confusion, cold and blue skin (especially around lips or fingers).  Less noticeable, but just as important, are weak pulse, irregular heartbeat and enlarged pupils.  Once you see that someone's stopped shivering, know that their core body temperature is dropping critically and they need immediate attention.


Chart A: How Cold Water Affects You
Water Temp Exhaustion Survival Time
32.5o f Under 15 min Under 15-45 min
32.5-40o f 15-30 min 30-90 min
40-50o f 30-60 min 1-3 hrs
50-60o f 1-2 hrs 1-6 hrs
60-70o f 2-7hrs 2-40 hrs
70-80o f 3-12 hrs 3hrs to indefinite
Over 80o f Indefinite Indefinite


How do you treat it?
The first and most obvious thing to do is get the victim to warm shelter.  That may be a hut, house or your car.  Send someone for help.

If help is nearby, make the victim as comfortable as possible, lay them on their back, cover him or her with a blanket or pile on some jackets or a sleeping bag.

If medical help will take a long time, apply heating pads or hot water bottles to the head, neck, chest and groin (make sure you cover them with a towel or other cloth so the victim doesn't get burned).  Don't put heat on the arms and legs or give the victim a hot bath!  That can actually be worse.  Don't massage or rub the victim, that's dangerous also.  If the person is alert, you can give them hot drinks (NEVER alcohol!

Chart B:  Wet Suit Protection

Water Temp Wet Suit Thickness
Over 80o f None (rash guard for sun)
60-79o f 2mm body 1mm arms/legs
"Spring" or vest
50-59o f 3mm body 2mm arms/legs
Full or "Steamer"
40-49o f 5mm body 4mm arms/legs
Below 40o f Dry suit

Disclaimer: Everyone reacts differently to cold water and every wet suit is different.  The comfort you get from a suit depends on a variety of factors including suit material, wind chill and your metabolism.  The ranges above are for reference only and should not be used when making your decision on a wet suitWe strongly recommend you discuss your selection with a wet suit manufacturer before purchase.

How do you prevent it?
Consider four ways your body loses heat:
  1. Respiration (heat escapes when we exhale)
  2. Evaporation (perspiration)
  3. Conduction (contact with cold water)
  4. Radiation (uncovered skin, e.g. head, hands, neck)

Protect yourself.  Wear a wet suit (Chart B has some "rules of thumb" about what thickness to get).  

Keep your feet and hands warm with surf booties and gloves.  Wear a surf hat or hood to prevent heat loss.  These items also block the wind, another source of chill.

Keep moving while you're in the water to burn calories that generate heat.

If you notice any of the symptoms of hypothermia, go to the beach and get warm.  Don't be afraid to ask for help.


Adventure Sports Online
Alaska Information Cache
Dr. Ernest Campbell
National Aquatic
Harvey's Skin Diving Supply 
Journal of the American Medical Association