National Weather Service Weather Forecast Office

Heat Index Values During The Current Heat Wave

Heat Index values during the current heat wave have reached dangerous levels the past four days. Extreme heat index values in excess of 100 are expected to continue into tomorrow across portions of central and southern Nebraska before a weak cold front brings a reprieve late tomorrow afternoon and evening. 

So what is the Heat Index? The Heat Index was devised as a way to measure how hot our human body perceives it to be taking into consideration both air temperature and relative humidity. Because our body perspirates to remove heat through evaporation, the more humid it is, the less of a cooling effect perspiration will have. As a result, hot and humid days will "feel" much hotter than hot and dry days.

The National Weather Service has devised a Heat Index chart which correlates Heat Index Values to possible exposure related heat disorders. 

The Heat Index table was devised for shady, light wind conditions, so care must be taken when one is exposed to full sunshine and/or breezy winds as this can exacerbate the effects of extreme heat on the body.

 Below is a listing of the Heat Index Values for the past four days which have exceeded 105 degrees.

Tuesday

Monday

Sunday

Saturday

Here is a map of high temperatures for Sunday, July 17th.