The Mississippi heat has always been part of high school football.
But beginning this season, when the heat reaches a dangerous level, outdoor practice must stop.
The Mississippi High School Activities Association is mandating the use of Wet Bulb Globe Temperature readings to determine whether conditions are safe enough for outdoor practices.
Under the MHSAA guidelines, no outdoor workout may continue when the WBGT reading rises above 92 degrees. Teams must stop outdoor activity and wait until conditions return to an allowable range.
That does not mean the temperature shown on a phone, television forecast or vehicle dashboard has reached 92 degrees.
Wet Bulb Globe Temperature measures the heat stress placed on someone working or exercising in direct sunlight. It accounts for factors such as air temperature, humidity, wind and solar radiation, giving schools a better picture of what conditions actually feel like to athletes practicing outside.
As the WBGT reading rises, schools must modify practices by increasing breaks, reducing equipment and limiting the length or intensity of outdoor activity.
Once the reading moves above 92, outdoor workouts are not allowed.
The mandate applies to more than football. The MHSAA posted the policy under several outdoor sports, including cross-country, soccer, fast-pitch softball, golf, tennis, track and field and baseball.
The timing is especially important for football.
Official practice begins Monday, August 3, with Mississippi teams entering a required acclimatization period designed to gradually introduce players to the heat, physical activity and protective equipment.
During the first week, players cannot wear shoulder pads. Certain lower-body protective pads and girdles may be worn, but full-length football pants are not permitted.
Shoulder pads may be introduced during the second week. Full-equipment practices are allowed only after players complete five full days in shorts and shoulder pads as part of the required 14-day acclimatization process.
The MHSAA is also placing additional attention on conditioning drills involving offensive and defensive linemen.
According to a WAPT report, linemen cannot be required to perform additional strenuous conditioning simply because of the positions they play. Coaches cannot make larger athletes complete extra running or demanding conditioning beyond what is required of the rest of the team.
That provision matters because larger athletes can face an increased risk of heat illness during intense outdoor activity, especially while wearing helmets, shoulder pads and other protective equipment.
Coaches still have a responsibility to prepare their teams physically.
They also have a responsibility to recognize when preparation becomes dangerous.
Football culture has always celebrated toughness. Players are expected to compete, push themselves and continue working when they become tired.
But there is a difference between building toughness and putting a young athlete in an unsafe situation.
No game, starting position or conditioning drill is more important than making sure every athlete returns home safely.
When the WBGT reading rises above 92, the message is clear:
Outdoor practice stops.