Baltimore Co. adopts new heat closure policy

The board of Baltimore County Public Schools adopted a policy at its meeting last week that will require the superintendent to close schools that don’t have air conditioning when the temperature gets too hot, the Baltimore Sun reports.

Temps during a normal summer day at BWI in Baltimore including heat indexHourly normals for BWI Airport (source: National Centers for Environmental Information/NOAA)

Specifically, schools that don’t have air conditioning, a number that grows lower as AC is installed one by one, will be preemptively closed if the heat index for the following day is forecast to reach 90°F. The district will try to announce the closure by 8 PM the night before.

The heat index is how hot it feels when relative humidity and sunlight are factored in with the air temperature. It is commonly reported as a “feels like” temperature on weather reports. More than 20 percent of the days (31 days) in a typical summer in Baltimore reach an air temperature of 90°F. The heat index is, on average, about 4°F higher than the air temperature.

But summers have been hotter in recent years, and climatological data from NOAA only takes into account years through 2010 (the administration revises the “normal” temperatures every so often, and the last time they did that, they included data only through 2010).

The Baltimore County policy only applies to schools that don’t have air conditioners installed and would not affect schools in which air conditioning units are broken in some rooms where students attend class.

In winter, meteorologists are more concerned with wind chill than heat index as the quality of weather that makes it uncomfortable.

Temps during a normal winter day at BWI in Baltimore including wind chill

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Paul Katula
Paul Katula is the executive editor of the Voxitatis Research Foundation, which publishes this blog. For more information, see the About page.