Massachusetts MIAA Heat Policy and WBGT Guidelines
The Massachusetts Interscholastic Athletic Association (MIAA) sets heat limits for high school athletics by Wet Bulb Globe Temperature (WBGT). Here are the activity limits at each level, and how Sports Safe applies them to your fields.
Outdoor practice stops
86.1°F WBGT and above
Massachusetts WBGT activity chart
No Flag
Under 76.0°F
Practice limit: None stated
Normal activities. At least three separate rest breaks each hour, minimum 3 minutes each.
Green Flag (low)
76.0 to 81.0°F
Practice limit: None stated
Use discretion for intense or prolonged exercise and watch at-risk players carefully. At least three separate rest breaks each hour, minimum 4 minutes each.
Yellow Flag (moderate)
81.1 to 84.0°F
Practice limit: 2 hours
Maximum 2 hours of activity. All sports: at least four separate rest breaks each hour, minimum 4 minutes each. If equipment modifications are necessary, no games should occur for that sport.
Equipment: Equipment-intensive sports: helmet, shoulder pads and shorts only. All protective equipment must be removed for conditioning activities.
Red Flag (high)
84.1 to 86.0°F
Practice limit: 1 hour
Maximum 1 hour of activity. 20 minutes of rest breaks provided during the hour of activity.
Equipment: No protective equipment may be worn. No conditioning activities.
Black Flag (extreme)
86.1°F and above
Practice limit: No outdoor practice
No outdoor workouts. Cancel exercise and delay activity until a cooler WBGT reading occurs.
| WBGT | Level | Practice limit | What the chart says |
|---|---|---|---|
| Under 76.0°F | No Flag | None stated | Normal activities. At least three separate rest breaks each hour, minimum 3 minutes each. |
| 76.0 to 81.0°F | Green Flag (low) | None stated | Use discretion for intense or prolonged exercise and watch at-risk players carefully. At least three separate rest breaks each hour, minimum 4 minutes each. |
| 81.1 to 84.0°F | Yellow Flag (moderate) | 2 hours | Maximum 2 hours of activity. All sports: at least four separate rest breaks each hour, minimum 4 minutes each. If equipment modifications are necessary, no games should occur for that sport. Equipment: Equipment-intensive sports: helmet, shoulder pads and shorts only. All protective equipment must be removed for conditioning activities. |
| 84.1 to 86.0°F | Red Flag (high) | 1 hour | Maximum 1 hour of activity. 20 minutes of rest breaks provided during the hour of activity. Equipment: No protective equipment may be worn. No conditioning activities. |
| 86.1°F and above | Black Flag (extreme) | No outdoor practice | No outdoor workouts. Cancel exercise and delay activity until a cooler WBGT reading occurs. |
Key points
- MIAA thresholds are much lower than Southern charts: outdoor workouts stop at 86.1°F WBGT. Games are allowed up to 86.0°F, but not for a sport that needs equipment modifications.
- Equipment-intensive sports at Yellow: helmet, shoulder pads, and shorts only, with all protective equipment off for conditioning.
- At Red: no protective equipment and no conditioning.
Common questions
- At what WBGT does outdoor practice stop in Massachusetts?
- Using the MIAA heat policy, Sports Safe stops outdoor practice at 86.1°F WBGT.
- How long can practice last at each heat level in Massachusetts?
- Under the MIAA heat policy, the practice time limits are: Yellow Flag (moderate), 81.1 to 84.0°F: 2 hours; Red Flag (high), 84.1 to 86.0°F: 1 hour. Levels not listed have no time limit stated, and at the top level outdoor practice stops.
- Does Sports Safe use the heat chart for Massachusetts automatically?
- Yes. Sports Safe uses the MIAA chart for fields in Massachusetts. You can choose a different chart for any field in its settings.
How Sports Safe uses the Massachusetts chart
Sports Safe estimates WBGT for each of your fields from current weather, checks it against this chart, and alerts you when a field moves into a stricter level. On the Organization plan, coaches can keep a timestamped log of meter readings and the actions taken.
An app estimate supports your decisions but is not a WBGT meter. Where your association requires readings from an approved instrument, use one for the reading of record.
Source
Summarized from the MIAA's published heat policy. View the source. Last reviewed October 3, 2026.
Sports Safe is not affiliated with or endorsed by the Massachusetts Interscholastic Athletic Association. Policies change, so always confirm the current rules with your association and follow your school's emergency action plan.