What is heat index?

KELOLAND.com Original

SIOUX FALLS, S.D. (KELO) — It’s been record hot weather for early June in Sioux Falls and many parts of KELOLAND. 

Despite the high temperatures for the first nine days of June, Thursday is the first day a Heat Advisory was issued. The Heat Advisory is in effect from noon to 8 p.m. CDT and 11 a.m. to 7 p.m. MDT. That kind of heat can cause heat illness.

Avera Health emergency medicine physician Dr. Alan Sazama said in 90 degree-conditions, heat exhaustion or heat stroke can begin to set in in 15 or 20 minutes.

Tips for dealing with Heat Advisory and Excessive Heat

  • Stay hydrated, drink plenty of water. 
  • Stay in an air-conditioned room.
  • Outdoor activities should be rescheduled to prevent heat exhaustion or heat stroke. 
  • Schedule frequent rest breaks in shaded or air conditioned areas.
  • Wear light weight and loose-fitting clothing when possible.
  • Young children and pets should never be left unattended in vehicles.
  • Heat stroke is an emergency, call 911.

A Heat Advisory is issued when the heat index value reaches 100 to 104 degrees. A Heat Advisory is the first tier of an extreme heat scale, similar to extreme cold temperatures with a Wind Chill Advisory and a Wind Chill Warning. 

After a Heat Advisory, there’s an Excessive Heat Watch and an Excessive Heat Warning. Excessive Heat Watch is issued when there’s potential for heat index to exceed 105 degrees, while the Excessive Heat Warning is issued when the heat index value is expected to reach or exceed 105 degrees. 

The Heat Index is a measure of how hot it truly feels when relative humidity is factored in with actual air temperature. Relative humidity is both moisture content and temperature. You can see an example of the Heat Index in a chart below.

Heat Index chart calculator.

You can get a list of weather alerts in each county on the KELOLAND Weather Alerts page. 

Energy tips for heat advisory and excessive heat warnings

Once temperatures get above 90 degrees for multiple days, energy concerns grow, officials told KELOLAND News.

Ben Pierson, Manager of Beneficial Electrification at Sioux Valley Energy recommends keeping the shades on your windows closed, keep the doors closed as often as possible and cook outside — do a little grilling.

As the heat increases, the cooperatives main concern is just “making sure the lights on.”

Learn about the approaching storm in-depth from the KELOLAND Live Doppler HD Storm Center in the latest forecast update from our meteorologists:

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