Wet-bulb globe temperature (WBGT) is the published gold-standard for heat-modification decisions in youth sport. KSI and National Athletic Trainers’ Association (NATA) both endorse it. WBGT factors in air temperature, humidity, radiant heat, and wind.
The problem: most youth programs do not own a WBGT reader. They cost $200 to $1,500. Many smaller programs make heat decisions on air temperature alone, which underestimates risk meaningfully.
For programs without WBGT, humidity and dew point are the backup metrics. Together with air temperature, they reproduce most of what WBGT captures. This piece is the framework.
Why humidity matters more than parents think.
The body’s primary cooling mechanism in heat is sweat evaporation. As sweat evaporates, it carries heat away from the skin.
When humidity is high, the air is already saturated with water. Sweat does not evaporate as efficiently. The cooling mechanism breaks down. A 90°F day at 80 percent humidity is more dangerous than a 95°F day at 30 percent humidity, even though the air temperature is lower.
This is why an 85°F practice in Florida or Louisiana in August can produce heatstroke while a 95°F practice in Arizona in the dry season often does not.
Dew point: the metric most parents have not heard of.
Dew point is the temperature at which the air would have to cool for condensation to form. It is a direct measure of how much water is in the air, independent of current air temperature.
Dew point ranges and what they feel like:
Below 55°F: comfortable, low humidity-stress.
55 to 60°F: pleasant for activity.
60 to 65°F: starting to feel humid. Light sweat-evaporation impairment.
65 to 70°F: humid. Noticeable impairment.
70 to 75°F: oppressive. Significant impairment.
75°F and above: dangerous. Very limited evaporative cooling possible.
Dew point above 70°F is the metric that most-reliably indicates heat-illness risk. NWS publishes dew-point forecasts; many weather apps include it.
The combined air-temp-and-humidity framework.
If your program does not have a WBGT reader, the practical framework:
Air temperature plus relative humidity together. NOAA’s heat index combines them. Apps like NWS Heat Index calculator are available.
The NWS heat index thresholds:
80 to 90°F heat index: caution. Fatigue possible with extended exposure.
90 to 105°F heat index: extreme caution. Heat cramps and exhaustion possible.
105 to 130°F heat index: danger. Heat cramps, exhaustion likely. Heatstroke possible.
Above 130°F heat index: extreme danger. Heatstroke imminent.
For youth-sport practice modification, modify intensity above 90°F heat index, consider canceling above 105°F.
Dew point thresholds for practice modification.
A practical framework programs without WBGT can use:
Dew point below 65°F: standard practice protocols. Hydration breaks every 30 minutes in heat.
Dew point 65 to 70°F: more frequent breaks. Pads off if not required. Monitor kids closely.
Dew point 70 to 75°F: shortened practices. Indoor option if available. No pads-on intensity work.
Dew point above 75°F: practice should be canceled, moved indoors, or moved to a cooler time of day.
These thresholds are conservative on purpose. The cost of canceling a practice is small; the cost of a heatstroke event is large.
The radiation question.
WBGT captures radiant heat (direct sunlight, surface temperatures). Air temperature plus humidity does not. The 90°F day with direct sun on a kid in full football pads is hotter than the same conditions in shade.
For programs without WBGT, the practical adjustment:
Shade decisions matter. Practice on a shaded field is meaningfully cooler than practice on a sun-exposed field.
Artificial turf adds heat. See the artificial-turf-temperatures piece. Turf practices need more conservative thresholds than grass practices.
Time of day matters. The 6 PM practice in mid-summer is often hotter than the 9 AM practice because the surface and structures have been heating all day.
Programs that should invest in a WBGT reader.
Football programs in the south.
Track and field programs running summer practices.
Tournament-host programs that schedule multiple games in summer heat.
Any program practicing in WBGT-elevated regions (Texas, Florida, Louisiana, Arkansas, Oklahoma, etc.).
The cost of a basic WBGT reader (around $200 to $400 for entry-level) is small relative to the liability and safety implications. Cheaper than one preventable heat-illness emergency room (ER) visit.
For coaches without WBGT.
The morning-of-practice routine in heat season:
Check air temperature, humidity, dew point, and forecast for the practice window. Most weather apps show this. NWS, Weather Underground, AccuWeather all work.
Calculate or look up heat index. Apply thresholds.
Modify practice accordingly. Earlier start time, indoor alternative, shortened duration, reduced intensity, more hydration breaks, pads-off start.
Communicate modifications to parents and athletes in advance.
For parents.
For a kid in a program in a heat-prone region, ask about the heat-modification protocol. A program that uses WBGT has done the work. A program that uses heat index and dew point is operating at acceptable level. A program that uses air temperature alone is operating below the published standard.
For tournament weekends, the question becomes the tournament organizer’s protocol. Worth asking before signing the kid up.
The honest read. WBGT is the gold standard and not every program has one. For programs without, the combination of air temperature, humidity, and dew point reproduces most of what WBGT captures. Dew point above 70°F is the simplest single metric for heat risk parents can check. The practical thresholds above provide a workable framework. Programs in heat-prone regions should invest in WBGT eventually; programs anywhere should at least be checking dew point in summer.