SPRINGFIELD, Ill. – A Heat Advisory will be in effect for the rest of the work week in Central Illinois, starting Wednesday.
The National Weather Service says highs will be close to 100 Thursday and Friday, with heat index values the next several days close to 110.
But what is the heat index? It’s a measure of actual temperature and relative humidity, making for what the heat feels like on the body.
“In those cases, when we’ve got that high relative humidity, that can take that heat index up well into the upper 90’s or even into the hundreds,” said Duane Friend, Climate Change Expert, University of Illinois Extension. “When we start getting in to that type of ‘feels like’ temperature, that’s really where we start seeing issues with our bodies and not being able to get rid of that heat.”
Friend says when the humidity is high, not as much sweat evaporates off our bodies, which then can lead to heat-related illness.
“Which means our internal body temperature starts to increase, and the more activity we do in those types of conditions, our body temperature starts going up. That’s when we can start getting in to issues with heat exhaustion, heat stress.”
Friend says there’s an even better read of how dangerous the outdoor heat can be. It’s called the “Wet Bulb Globe Temperature” – often used in marathons and in the military among other places, to determine how direct sunlight on the human body causes heat-related stress.
(National Weather Service)
