Coach's and Parent's Guide to NFHS Heat and Hydration Youth & High School 2025

The NFHS heat statement (October 2025) says to start slowly and build up progressively. An athlete can't be "conditioned" in only two to three weeks.

In the first several practices:

• Hold shorter, less intense sessions with longer recovery breaks between bouts.
• Keep protective gear to a minimum, then add uniform and equipment pieces over successive days.
• Teach more than you condition.

Why it matters: most heat-related deaths happen in the first few days of practice, usually from doing too much too soon, and sometimes from wearing full protective gear too early.

Throughout the season: athletes must start every practice well hydrated, coaches should have a hydration plan with plenty of chances to drink, and activity should be adjusted to the heat and to each athlete's fitness and health.

NFHS says there's no one-size-fits-all acclimatization plan. For high school sports, each state association builds its own plan, so details such as limits on practice length or double sessions vary by state.

The NFHS heat and hydration statements (October 2025) say risk is higher for athletes who:

• are unfit or not yet used to the heat (poorly acclimatized)
• have obesity or a high body-fat percentage
• are ill or were recently ill, especially with vomiting, diarrhea or fever
• take certain medications that affect hydration or temperature control
• have had exertional heat illness before
• have sickle cell trait
• play football, especially linemen

"Salty sweaters", who leave visible salt stains on clothes and skin, often have a higher risk of exertional muscle cramps.

NFHS says coaches should keep each athlete's conditioning and medical status in mind and adjust their activity to match. Parents: make sure the coach (and the athletic trainer, if there is one) knows about any of these, including a recent illness or a new medication.

NFHS guidance (October 2025) says to follow a heat safety table to decide whether to start, modify or stop practices and games.

• Wet Bulb Globe Temperature (WBGT) measured on site is the "gold standard" for heat stress. Take the reading 10 to 15 minutes before practice or a game and compare it with a heat safety table, such as the National Athletic Trainers' Association (NATA) WBGT guidelines.
• No WBGT device? Use the heat index for your location instead.
• Humidity matters, not just temperature. 95°F with 40% relative humidity carries a likely risk of heavy sweat loss and heat illness during strenuous activity. The risk at just 85°F with 70% or higher humidity is likely the same or greater.
• Watch for irrigation. Sprinklers run before early-morning practice can raise humidity on the field even in dry climates.

As conditions get hotter or more humid, coaches should lower intensity, give more frequent and longer rest breaks, consider reducing uniform and equipment, and watch athletes more closely, especially when the weather has changed from the previous few days.

State rules can differ. Your state athletic association may set its own heat guidelines for your region, and NFHS recommends following state or regional guidelines strictly.

NFHS hydration guidance (October 2025) gives this example schedule:

Notes:

• Athletes who sweat a lot can safely and comfortably drink up to 48 oz per hour during activity.
• Drink regularly throughout activity. Don't wait until thirsty, because thirst means early dehydration has already started.
• The after-activity amount is meant to restore normal hydration before the next practice or game, when there's enough time to do it safely and comfortably. Drinking an excessive amount in a short time can be dangerous.

For parents: send your child with enough fluid to follow this schedule. Coaches should give athletes plenty of chances to drink.

Water is right for most athletes in most situations, according to NFHS hydration guidance (October 2025). It's quickly absorbed, well tolerated and inexpensive.

A traditional sports drink may help when:

• activity lasts more than 60 minutes, continuously or on and off
• there are several intense sessions on the same day
• conditions are warm to hot and humid
• the athlete started poorly hydrated, sweats heavily or is a "salty sweater" (visible salt stains on clothes and skin), hasn't eaten enough, or isn't used to the heat

Choose a sports drink with no more than 6 to 8% carbohydrate and 0.4 to 1.2 grams of sodium per liter.

Avoid during exercise:

• Energy drinks. NFHS says they are NOT appropriate hydration fluids. They're high in sugar and caffeine, can cause jitteriness, nausea and upset stomach, can increase dehydration, and aren't regulated by the FDA.
• Carbonated soda, and fruit juices over 8% carbohydrate. Both can cause bloating and stomach cramps.

NFHS guidance (October 2025) gives two practical checks.

1. Urine color and amount

• Small amounts of dark urine mean the athlete needs to drink more.
• A regular amount of light-colored or nearly clear urine (straw yellow, "the color of lemonade") generally means they're well hydrated.

2. Weight before and after practice
Coaches can weigh athletes before and after practice, because weight lost during exercise is mostly water.

Don't rely on thirst: by the time an athlete feels thirsty, they're already mildly dehydrated. Athletes who start practice already dehydrated hit these limits sooner.

Yes, though it's rare. NFHS hydration guidance (October 2025) warns about hyponatremia: a potentially deadly condition caused by drinking far more water or other low-sodium fluid (including most sports drinks) than is lost through sweat. Too much water dilutes the sodium in the blood to dangerous levels.

• It's most common in endurance events, such as marathons, when people drink large amounts over several hours.
• Signs: disorientation, altered mental status, headache, lethargy and seizures.
• Suspected hyponatremia is a medical emergency. Call 911. It can only be confirmed with a blood test and is treated in hospital with high-sodium IV fluids.

When rehydrating after exercise, NFHS cautions that drinking an excessive amount in a short time can be dangerous.

NFHS hydration guidance (October 2025) says dark or bulky clothing and protective equipment such as helmets, shoulder pads and other padding raise body temperature and sweat loss, which increases the risk of dehydration and heat illness.

What this means in practice:

• Choose light-colored, lightweight practice clothing where the sport allows.
• Early in the season, protective gear should be added gradually. The NFHS heat statement says to keep gear to a minimum in the first several practices and add uniform and equipment pieces over successive days.
• As heat and humidity rise, coaches should consider reducing uniform and protective equipment as well as lowering intensity.

Most heat-related deaths happen in the first few days of practice, often from doing too much too soon, sometimes in full gear too early in the season.

Early signs of distress: NFHS (October 2025) says athletes often show early signs of developing heat illness. If you spot them and act promptly by stopping or easing the activity, resting and treating the athlete, serious injury can usually be avoided. The athlete can often return once the signs and symptoms have resolved. Don't delay first aid.

Serious signs (possible exertional heatstroke):

• Clumsiness or stumbling
• Collapse
• Obvious behavior changes or other central nervous system problems

If you see serious signs:

1. Stop the activity immediately.
2. Call 911 (activate EMS).
3. Start rapid cooling on site right away, ideally by immersing the athlete in a tub of cold or ice water, or using a tarp (the "TACO" method).
4. Cool first, transport later. Immediate rapid cooling can prevent death.

Exertional heatstroke is the leading preventable cause of death in high school athletics.

The NFHS heat statement (October 2025) says every program should have a written, practiced Emergency Action Plan (EAP) in place before the season, covering:

• All teams, including freshman, junior varsity and varsity
• All practice and game sites
• Rapid cooling on site. Cold-water tubs, pools, or tarps for the "TACO" method should be available, and staff should be trained and practiced in using them.
• Cool first, transport later. For heat emergencies, the plan should stress cooling the whole body before transport to hospital.

Training: NFHS says its NFHSLearn.com online course "Heat Illness Prevention" should be made available to all coaches, and every member of the coaching staff should be able to recognize the signs of developing heat illness.

States vary: NFHS urges each state association to build all of its heat "Fundamentals" into a heat acclimatization plan, but plans can differ by state and climate.

The NFHS heat statement (October 2025) says football has the highest rate of exertional heatstroke of any American sport. According to recent reports it cites, 100% of high school and college football heatstroke deaths happened during conditioning sessions, and linemen made up 97% of football heatstroke deaths. Linemen heat up faster and cool down more slowly than other players.

NFHS recommendations:

• Make all training and conditioning position-specific, and train linemen for what games actually demand.
• Modify activity for the heat load.
• Never use exercise as punishment.
• Drop conditioning tests, serial sprints and other reckless drills that aren't appropriate for linemen.
• Consider air-conditioned venues for linemen during hot practices.
• Recognize that some players have a "do or die" attitude that overrides their own safety.
• Bring in helmets, shoulder pads and other gear gradually over the first several practices.