This stereotypical winter danger is actually a year-round killer

Summer may be winding down, but that doesn’t mean the boats and bathing suits have been put away just yet. Many are still flocking to the dock to spend time on the water.

But be warned – the water temperature you feel when waist deep doesn’t tell the full story.

Last month, the surface temperature of Lake Michigan was reported at 82° F – measured in St. Joseph, MI. But just 48 hours later, the same recorded location’s temperature had dropped to 58° F.

According to the National Center for Cold Water Safety, any water below 70° F should be treated with caution. And the National Weather Service says roughly 20 percent of those who fall into cold water die within the first minute of immersion due to cold water shock.

“Summertime exposure to the cold is more likely to turn into a deadly situation because people are often unprepared for it,” says Dr. Elizabeth Byrne, an emergency medicine physician at Advocate Illinois Masonic Medical Center in Chicago. “Hypothermia occurs when the body’s core temperature drops below 95° F, causing a loss in body functions. Effects range from shivering to severe symptoms such as altered mental status and cardiac arrest. Hypothermia can occur any time of year in any climate. Chicago summer nights can sometimes feel like winter nights!”

Even when the air is hot, rivers and lakes can remain far below human body temperature. Cold water can kill even before hypothermia begins, warns the National Weather Service. The shock of falling into water often triggers a gasping reaction. If you cannot control your breathing within a minute, you can begin inhaling water and drown. After 10 minutes, you begin to lose muscle control, impairing your ability to swim or float. With a life jacket, most people can float for one hour before losing consciousness from hypothermia.

Dr. Byrne offers the following tips for handling hypothermia:

• Prepare for the water temperature, not the air temperature. Bring dry clothes and blankets when boating. Avoid cotton–it’s a poor insulator and is heavy. If possible, wear a wicking fabric and/or modern, watertight materials like nylon and Gore-Tex.
• Minimize heat loss. If your boat capsizes, climb onto it and pull yourself out of the water. If you have no personal flotation device and nothing to climb onto, tread water. Remain as still as possible to conserve energy. Avoid swimming unless a shore, raft or other destination is nearby.
• Treat symptoms of hypothermia immediately. Remove any wet clothes and provide warm, dry blankets. Warm the center of the body first—chest, neck, head and groin. Call 911 immediately if the victim shows signs of severe hypothermia (unconscious and no pulse, not breathing, etc.). Even if they seem dead, perform CPR until the ambulance comes.
• Know first aid and CPR basics. They can save lives!