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Heat haze over an open playing field at midday, the kind of humid afternoon the WIAA heat and humidity policy covers at Wisconsin schools

State heat policy · Wisconsin (WIAA) · Checked 15 Oct 2026

Wisconsin high school heat policy: WIAA heat index tiers, water breaks, and how to plan around them

The WIAA's Model Policy for Heat and Humidity sets four heat index tiers that decide water breaks, equipment and uniforms, and the point at which all outside activity stops. Readings are taken at the site before and during activity and kept on file. Here are the tiers as the WIAA prints them, what to keep on file, and how a 6-hour outlook lets you move practice instead of cancelling it.

Flash Meteorology Desk · Checked against the WIAA Model Policy for Heat and Humidity (wiaawi.org) · Checked 15 Oct 2026 · 6 min read

Heat index outlook · Field B · 6 hours

12:58

99.082921 pm2 pm3 pm4 pm5 pm6 pm
  • 4 pm · 101 — above 99
  • At or under 99 after 5:00

Move practice to 5:30 — the on-site reading stays the record.

Illustrative example · Not live weather
On this page · 8 sections

What does the WIAA recommend?

The WIAA publishes a model policy for heat and humidity, with the football acclimatization policy kept separately in the football season regulations. Temperature and humidity readings are taken at the site 30 minutes before an activity starts and again 60 minutes after it starts. A digital sling psychrometer or a Wet Bulb Globe Thermometer is recommended; without one, the heat index is calculated from temperature and humidity using the National Weather Service calculator.

Readings are recorded in writing and kept in the files of school administration. Each school designates who handles this, generally the athletic director, head coach or certified athletic trainer. When the air temperature is below 80 degrees, no combination of heat and humidity requires activity to be curtailed.

  • Reading cadence

    30 minutes before the activity and 60 minutes after it starts. From a heat index of 95, recheck every 30 minutes.

  • Records on file

    Readings recorded in writing and kept in the files of school administration, by a designated person.

  • The instrument

    A digital sling psychrometer or Wet Bulb Globe Thermometer is recommended; otherwise calculate the heat index.

  • Water and cooling

    Water always available in any amount athletes want, and ice-down towels for cooling at every tier.

The WIAA heat index table

Four tiers, read as heat index in degrees Fahrenheit. The row colour follows the Flash alert scale your athletic trainers already see in the app.

WIAA Model Policy for Heat and Humidity heat index tiers for Wisconsin high school sports: below 95, 95 to 99, above 99 to 104 and above 104, with activity, water-break and equipment rules
Heat index (°F)ActivityWater breaksContact sports and equipment
Below 95Watch/monitor athletes carefully for necessary action. Ice-down towels for coolingOptional water breaks every 30 minutes for 10 minutes in durationNone listed
95 – 99Watch/monitor athletes carefully for necessary action. Ice-down towels for coolingOptional water breaks every 30 minutes for 10 minutes in durationHelmets and other possible equipment removed while not involved in contact. Reduce time of outside activity. Consider postponing practice to later in the day. Recheck temperature and humidity every 30 minutes to monitor for increased Heat Index
Above 99 – 104Alter uniform by removing items if possible. Allow for changes to dry t-shirts and shorts. Reduce time of outside activity as well as indoor activity if air conditioning is unavailable. Postpone practice to later in the dayMandatory water breaks every 30 minutes for 10 minutes in durationHelmets and other possible equipment removed if not involved in contact or necessary for safety. If necessary for safety, suspend activity. Recheck temperature and humidity every 30 minutes to monitor for increased Heat Index
Above 104Stop all outside activity in practice and/or play, and stop all inside activity if air conditioning is unavailable——

Source: WIAA Model Policy for Heat and Humidity (wiaawi.org), checked 15 Oct 2026. Tiers as printed, in heat index, not WBGT. At every tier: provide ample amounts of water, always available. When the temperature is below 80 degrees there is no combination of heat and humidity that will result in need to curtail activity.

Where does Flash fit?

Flash is a forecast for planning, not an on-site meter: the WIAA policy runs on the reading taken at the activity site. Flash's 6-hour outlook includes heat index for every hour, so at 1 pm you can see what the 4 pm reading is likely to be and move practice instead of cancelling it.

  • Heat: plan, don't cancel

    The outlook runs per field for every hour of the afternoon, against the WIAA tiers. Shift the start, swap the equipment plan or go indoors before the cars arrive.

  • Lightning: up to 60 minutes ahead

    Strike-level prediction on a 1×1 km cell, refreshed every 2 minutes. Up to 99.6% lightning prediction accuracy on a one-hour window, measured against NLDN ground-truth strikes — method published.

    Accuracy method

  • Return to play: the all-clear timer

    After the last strike inside your radius, Flash runs your policy's all-clear timer and logs it, so play resumes on evidence.

    Weather Command Center

Flash Heat and WBGT prediction 6-hour WBGT outlook, heat index, air temperature and dew point per 1×1 km cell

What does a planning day look like?

Illustrative example · Not live weather — the readings are examples, the rules are the WIAA's

An empty high school practice field under a hazy hot sun with a shade canopy and water coolers on the sideline, the setting for a WIAA heat index planning day in Wisconsin

6:00 pm · The reading that decides the day

The tier you land in sets the water breaks, the uniform and the pads.

  1. Flash 6-hour outlook for the practice field: heat index 98 by 3 pm, above 99 by 4 pm. The athletic director flags the football session.

  2. Decision: run at 4 pm with mandatory water breaks and pads off, or push to 6:30 pm, as the policy says to postpone practice to later in the day. The AD pushes. The bus, the trainers and the parents hear now.

  3. Reading at the site 30 minutes before practice: heat index 96, the 95–99 tier. Helmets come off when players are not in contact, and the next reading is set for every 30 minutes.

  4. Flash lightning alert: a strike is predicted inside the site radius within the next 60 minutes. The field clears.

  5. Last strike inside the radius. Flash starts the all-clear timer.

  6. All clear. Practice resumes; the alert log records who was warned, when, and when play returned.

What should the athletic director keep on file?

The WIAA model policy has readings recorded in writing and kept in the files of school administration. Keep these together so a question from the WIAA, the district or a parent is answered from one folder.

  • Temperature and humidity readings with times: 30 minutes before the activity, 60 minutes after it starts, and every 30 minutes from a heat index of 95.
  • Who the school designated to take readings: the athletic director, head coach or certified athletic trainer.
  • The tier each reading fell in and the decision it triggered: water breaks, equipment, uniform, postponement.
  • The football acclimatization record under the WIAA football season regulations.
  • The Flash alert log: lightning alerts, who was notified, the all-clear, and the 6-hour outlook the schedule decision was based on.

Which other states publish WBGT policies?

Every state page follows this template: verified thresholds, the reading cadence, what to keep on file, and where the WBGT forecast fits.

Heat haze over an open field at midday, the conditions each state association's WBGT policy sets practice limits for

State by state

Same instrument, different bands — the WBGT forecast travels with you.

All state heat policies

Sources

  1. WIAA (Wisconsin) — Model Policy for Heat and Humidity. Heat index tiers, reading cadence, records. Checked 15 Oct 2026.wiaawi.org/sites/default/files/pdfs/PDF/Health/MODEL-POLICY-HEAT-AND-HUMIDITY.pdf (opens in a new tab)
  2. WIAA (Wisconsin) — Weather page, Health & Safety, linking the model policy. Checked 15 Oct 2026.wiaawi.org/athletic-resources/health-safety/weather (opens in a new tab)

WIAA documents are published at wiaawi.org (opens in a new tab).

Frequently asked

No. The WIAA policy runs on temperature and humidity readings taken at the activity site. Flash's 6-hour outlook tells you where the heat index is heading — a scheduling tool, not a compliance instrument.

The tiers are in heat index. A Wet Bulb Globe Thermometer or digital sling psychrometer is recommended for readings; without one, the heat index is calculated from temperature and humidity.

Above a heat index of 104, all outside activity stops, in practice and play, and inside activity stops too if there is no air conditioning.

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