Quick Answer
Temperatures around 40°F (4°C) and wind speeds above 25 mph (40 km/h) can cause hypothermia, especially in wet or cold conditions. Prolonged exposure increases the risk of hypothermia.
Wind Chill Factors
Wind chill, a measure of how cold it feels outside, plays a significant role in hypothermia risk. Wind speeds above 20 mph (32 km/h) can significantly lower the perceived temperature, increasing the risk of frostbite and hypothermia. Using the wind chill chart, we can estimate the wind chill temperature by adding 15°F (8.3°C) to the air temperature for every 10 mph (16 km/h) of wind above 20 mph.
Water Temperature and Hypothermia
Water temperatures below 50°F (10°C) can cause hypothermia within 60-90 minutes, even in dry conditions. For example, if the air temperature is 40°F (4°C) and the water temperature is 45°F (7°C), the risk of hypothermia increases significantly. In wet conditions, hypothermia can set in much quicker, often within 30 minutes to an hour.
Hypothermia Risk Assessment
When assessing the risk of hypothermia, consider the following factors: air temperature, water temperature (if applicable), wind speed, and clothing. If you’re exposed to wind speeds above 25 mph (40 km/h) or water temperatures below 50°F (10°C), take immediate action to prevent hypothermia. This may include seeking shelter, changing into dry clothing, and using warm bedding or a space blanket to retain body heat.
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