Because children tolerate heat and humidity less well than adults, there may be times when it will be necessary to modify or even cancel practices due to extremely hot or humid conditions. In deciding whether to do so, you should keep in mind the following.
- Hot, dry weather can be extremely dangerous. Because sweat evaporates very quickly in such conditions, your child won't feel sweaty, and neither you nor your child may recognize how much water he or she has lost.
- As the relative humidity increases, the effectiveness of sweating in cooling the body decreases.
- When the relative humidity is high, sweat drips off the skin so that the cooling benefit of evaporation is lost even at cooler temperatures, resulting in a build-up of body heat.
Modify or cancel practice based on the air temperature and the humidity (apparent temperature), which can be measured with a wet bulb thermometer available at hardware stores:
For wet bulb readings below 66 F (or when the relative humidity is 95% or higher, regardless of wet bulb reading), no precautions are needed, but watch closely children who are prone to heat illness.
If the wet bulb temperature is between 66 F and 78 F (or when the relative humidity is 95% or higher, regardless of wet bulb reading), be cautious. Insist on unlimited amounts of water (preferably iced), and that all athletes be monitored closely for symptoms of heat illness.
For wet bulb temperature readings above 78 F (or when the relative humidity is 95% or higher, regardless of wet bulb reading), modify practicebecause there is a real danger for serious heat illness. Keep practice light, modify or eliminate some drills, and allow athletes to work out in minimal gear. Water breaks in the shade should be mandatory. Do not allow children who lose weight during exercise to participate.