English Channel Water Temperatures
Water temperature. This is between 59°F and 64.5°F (15°C to 18°C). The temperature is around 59°F to 60°F at the end of June beginning of July, then rises slowly to 64/65°F by the end of August beginning of September, then it usually drops by a couple of degrees before the beginning of October. There are however exceptional years like 1995 when the water temperature reaches 67°F (19°C). Try to train in temperatures around 60°F (15.5°C). There is no need to train in water that is too cold (below 55°F/12°C ) and do not convince yourself that if you are swimming in 70°F/21°C then it is almost the same.
Bi-lateral breathing. Train yourself to breathe bi-laterally. This will mean that you can swim on either side of the escort boat using the shelter of the hull if the wind gets up or avoiding the exhaust fumes if the wind is in the wrong direction.
Air temperature and chill factor. This varies considerably depending on the weather and the hours of daylight. The longest day is about the 21st of June, giving daylight from about 0330 to 2200 hours. This decreases to 0600 to 1900 hours by the end of September. Body heat is lost from the parts of the swimmer exposed to the air (head and shoulders, etc.). The air temperature is higher during daylight hours, therefore the longer the day, the greater the period of higher air temperature, and the smaller the loss of body heat.
Hypothermia. The normal body temperature is 98.4°F (37°C). Hypothermia develops when the body temperature falls below about 95°F (35°C). Moderate hypothermia can usually be reversed, and a complete recovery made if it is recognised and treated quickly. However, if the body temperature falls below 75°F (24°C), recovery is unlikely. The symptoms and signs of the onset of hypothermia are difficult to recognise to the inexperienced eye. They are basically bouts of shivering, disorientation, irrational behaviour, blueness of the lips, inability to concentrate or co-ordinate speech, and inability to respond to simple requests or questions. If hypothermia arises your team must do as they are instructed - your life may depend on it!