The ten warmest consecutive 12-month periods in recorded history for the United States have occurred since 2000, according to the U.S. National Oceanic and Atmospheric Administration. August 2011 to July 2012 was the warmest 12-month period that the contiguous United States has ever experienced; July registered as the warmest month the nation has ever seen, eclipsing a record set in the Dust Bowl, according to NOAA.
Might there come a time when the climate in the South is just too oppressive for summer football workouts?
"I think you can do it safely, but you have to really monitor," Grundstein said. "I do think it's really important to have a policy in place because you're only going to get more days that are really oppressive."
Coach Herron, however, says the real problem today isn't the heat, but the kids' lifestyles.
"It's not any different," Herron said of the heat these days. "The difference is that when we were kids, we were out playing all summer. We were outside, we weren't laying in the air conditioning."
So that kids don't jump from the air conditioning into the oven, Georgia's new heat rules require an acclimatization period of five days – practice in helmets only – before players are allowed to suit up in full pads on Aug. 1.
Georgia's rules were based on a study by athletic trainers at the University of Georgia, who presented their unpublished work at the annual meeting of the National Athletic Trainers' Association last summer and to the Georgia High School Association's football subcommittee in January.
The researchers say they found that the first weeks of preseason practice are when the risk of heat related illness is greatest.
To lessen the risk, Georgia's high school football overseers this year adopted heat guidelines similar to those published by the National Athletic Trainers' Association [PDF] in 2009. Three-a-day practices are now banned. Teams cannot have two practices per day on consecutive days. Because many teams lift weights in tin sheds that lack air conditioning, weight training now counts as practice time.
Every team in Georgia is now required to have a "wet bulb globe temperature" meter on the practice field. The metric incorporates air temperature, humidity and radiant temperature. The reading tells the athletic trainer or coach what the weather feels like down on the field; if the reading passes certain cutoff points, practices must be shortened or equipment shed.
"The more equipment that you have on, the body's ability to remain in a cool, safe temperature becomes impacted," said athletic trainer Bud Cooper of the University of Georgia and a study co-author. "As that (wet bulb globe temperature) goes higher and higher, in order to allow the athlete to continue to participate, modifications need to be made to allow him to stay cool."
At a wet bulb globe temperature reading of 92, equivalent to a heat index of about 105, outdoor practice must be cancelled.
No helmets or pads
Before Georgia's heat rules began, the Marietta High School Blue Devils in metro Atlanta, one of the teams studied by Cooper and colleagues, practiced under stricter standards than the state now requires. For years, they used a wet bulb globe temperature reading of 88 as their cut-off point for practice. But by using flexible practice times and creative practice schemes, they never missed a practice, said Marietta High's athletic trainer Jeff Hopp, who is also president of the Georgia Athletic Trainers' Association.