Cincinnati weather: When is it too hot to practice outside? Ohio, KY differ on guidelines

The August heat has been hitting hard and as extreme heat rises and rises throughout the week, local athletic programs must monitor the heat for player safety.

Several programs have had to deal with the weather by canceling events or pushing back starting times to allow the effect of heat and humidity to lessen.

What guidelines do Ohio and Kentucky high schools have for combating extreme temperatures? It all starts with the Wet Bulb Globe Temperature.

What is the Wet Bulb Globe Temperature?

Knowing the safe temperatures and conditions for athletes to compete isn't just getting the weather report on the morning news or from the app on a phone.

Organizations such as the Occupational Safety and Health Administration (OSHA) have moved away from the heat index and recommend utilizing WBGT to assess environmental heat. Based on recommendations from the National Federation of State High School Associations, both the Ohio and Kentucky High School Athletic Associations have made similar switches to measuring via WBGT (with the KHSAA allowing heat index as an optional choice until the end of the 2023-2024 season). The Indiana High School Athletic Association goes with the heat index.

The WBGT is measured in direct sunlight and takes the ambient temperature, humidity, wind and sun and cloud cover into consideration for calculation. The idea is that the WBGT takes into consideration all of the conditions that an athlete would play through as opposed to just regular temperature readings.

Heat index takes into account just the humidity and ambient temperature but for shady areas as opposed to areas in direct sunlight.

Wet Bulb Globe Temperature has no conversion charts to calculate the WBGT from other measurements. A specialty on-site device must be used at the location of practices or games. The KHSAA has measuring procedures that include: the monitoring device placed three to four feet above the playing surface, leaving the device exposed to conditions for more than 15 minutes before activities begin. Contest or location officials should take measurements every 30 minutes during the competition.

What heat limits do Ohio and Kentucky follow?

The OHSAA and KHSAA have guidelines for avoiding heat illness about requiring water and sports drinks at all times or having cold tubs ready for cooldowns, but their WBGT guidelines have slight differences.

In Ohio, the OHSAA recommends:

• WBGT less than 79.7 degrees: Normal activity; three breaks of three minutes in length per hour
• WBGT from 79.8-84.6 degrees: Helmets and equipment removed when not directly in competition; three breaks of four minutes in length per hour
• WBGT from 84.7-87.6 degrees: Consider postponing practice to later in the day; maximum practice time of two hours; allow participants to change into dry clothes; football should limit to helmet, shoulder pads and shorts for practice; four breaks of four minutes in length per hour
• WBGT from 87.7-89.7 degrees: No additional conditioning; football and lacrosse are not permitted to use helmets, shoulder pads or other equipment; maximum of one hour of practice with four breaks of five minutes in length within the hour
• WBGT greater than 89.8 degrees: No outdoor workouts; no indoor workouts unless air-conditioned.

In Kentucky, the KHSAA requires:

• WBGT less than 82 degrees: Normal activity; three breaks of three minutes in length per hour
• WBGT from 82.1-87 degrees: Watch at-risk players carefully; three breaks of four minutes in length per hour
• WBGT from 87.1-90 degrees: Maximum practice time of two hours; football, lacrosse and field hockey athletes should remove helmets and shoulder pads for practice; four breaks of four minutes in length per hour
• WBGT of 90.1-91.9 degrees: Maximum practice length of one hour; football, lacrosse and field hockey should not wear any protective equipment during practice; no additional conditioning activities permitted; 20 minutes of rest breaks distributed in the hour's practice
• WBGT greater than 92 degrees: No outdoor workouts; delay practice until the WBGT has decreased.

What does Indiana use?

The IHSAA uses a chart defining the heat index based on temperature and humidity. The IHSAA also requires a period of heat acclimatization during the first two weeks of fall football practice. The liquid of choice for hydration is water, but say a sports drink may be advised after 45 minutes of practice.

• Caution at 80-90 on the heat index: Fatigue is possible with prolonged activity or exposure
• Extreme caution at 91-105: Sunstroke, muscle cramps and heat exhaustion are possible with prolonged activity or exposure.
• Danger at 106-129: Sunstroke, muscle cramps and heat exhaustion likely; heatstroke possible with prolonged activity or exposure.
• Extreme danger at 130 or higher: Heatstroke or sunstroke likely