Student athletes and marching band members across Texas may see shorter, delayed or even canceled outdoor practices this school year under new heat safety rules now required by the University Interscholastic League (UIL). It factors in humidity, wind speed and solar radiation to determine the amount of heat stress a person experiences outdoors. Schools must record the WBGT at least 15 minutes before outdoor practices begin and every 30 minutes while activities are underway. "Here in Houston, we joke it's not the heat, it's the humidity," Ifedi said. Because of the new guidelines, many schools are scheduling outdoor practices during cooler parts of the day, such as early morning or evening hours.