WRAL WeatherCenter Blog

Heat index climatology - a new tool

Posted July 19, 2010

Hourly counts of heat index 100 degrees or higher at the Raleigh-Durham airport for the years 1980 through mid-July 2010. Dark red/maroon indicates hours with heat index 110-114, while light orange indicates hours reaching 100-104.

In looking for some heat index-related information recently, I came across a fairly new addition to the many useful and informative products offered (and frequently added to) by the folks at the State Climate Office of North Carolina, located just down the road from our studios on the NCSU Centennial Campus.

If you'd like to see how frequently your area climbs into the very uncomfortable or even dangerous range of heat index (hot temperatures combined with elevated humidity levels that reduce the body's cooling efficiency), you can check out a page that allows you to select the city of interest and the pull up either tabular statistical data or graph that data for a sense of what is typical, how often extreme values occur, and how variable higher levels of heat index can be from year to year.

I took a look at data from the Raleigh-Durham airport for the years 1980 through 2010 (so far) and found that, for example, we average 13 hours per year with a heat index in the range of 105-109 degrees and 2 hours per year at 110-114, and in all those years have reached 115 for a heat index for only one hour. While we average 2 hours per year at 110 or higher, we have had 4 years with more than 5 hours at that steamy level, and quite a few in which that threshold is never reached. 1981, 1999 and 2007 stand out as especially hot and humid years, while in 1985 we only cracked the 100-degree mark in heat index for one hour the entire summer, and for only 7 hours in 1982. All of that is available at the link I've included, and you can see it in graphical form in the image I posted for the RDU 1980-2010 data.

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  • carnival glass Jul 19, 2010

    Hey, thanks for the link. The humiditiy this year seems intense. I'm ready for October (my favorite weather month).