Cold water shock: Be aware of this lesser-known danger before hitting the water this summer

By Brian Lada, AccuWeather meteorologist and staff writer

As the summer heat builds and people start to spend more time outdoors, lakes and rivers may still be dangerously cold following the winter months.

“Typically, in the spring and early summer is when people start venturing out onto the water and [they] don’t quite realize what they’re getting into with how dangerous the cold water is,“ said Keith Bills, course manager at the National Ice Rescue School for the Coast Guard.

Even on days when the weather is sweltering hot, the water in rivers and lakes may lead to a dangerous condition called cold water shock.

This is especially true in the western Unites States where many rivers and lakes are fed by snowmelt from the mountains, causing them to be cold year-round.

Kayaking AP

Denise Gravatte works to stay upright while kayaking the white water of the Warner River in Warner, N.H., Sunday, April 18, 2010. (AP Photo/Jim Cole)

Cold water shock is the body’s immediate response to entering a cold body of water and can trigger a reflex to gasp in air which may be fatal.

“If you have not conditioned yourself, you may automatically and uncontrollably inhale water when you go under,“ Bills said.

If someone is not nearby to help right away, this reflex may lead to drowning seconds after entering the water.

Cold water shock can also lead to hyperventilation and the feeling of suffocation, which may make it difficult to swim to safety or even stay afloat until the initial shock of being submerged in water subsides.

However, this does not mean that people should avoid cold rivers and lakes if the proper steps are taken.

“You can go in the water, just go in slow, gradually and become accustomed to it and be careful about just jumping into cold water,” Bills said.

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Once the initial shock has passed, the second phase of cold water immersion starts to settle in with a loss of mobility in arms and legs.

Any water at or below 77 F is considered to be cold water, and the lower the temperature, the quicker it will begin to affect the body.

Although 77 F may not sound cold, it is the point at which the body can no longer generate enough heat to stay warm. As a result, the human body will naturally react to preserve the vital organs in the body’s core by decreasing blood flow to the arms and legs.

“[Short-term immersion causes] the loss of performance where you get cold muscle tissue and you lose the ability to even swim, move your arms or even hold onto anything,“ Bills said.

This is one reason why wearing a life jacket is crucial when spending time in water or on a boat.

Being submerged in cold water will eventually lead to hypothermia, which can be fatal if not treated immediately and in the proper manor.

It is important to know the dangers of cold water before stepping foot in the water or on a boat.

Following a few safety tips may help to save your life:

  • Always wear a life jacket.
  • Never go out in the water alone.
  • Have a way to contact help if a water rescue needs to be performed.
  • Practice how to get to safety when entering the water. If you are going out on the water in a kayak or canoe, know how to get back in the vessel if it overturns.
  • Do not assume that the water is warm just because the air temperature is high.
  • Ease into cold water gradually so that the body can acclimate to the conditions.

For more safety and preparedness tips, visit

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