ST. LOUIS – When we start throwing words around like “historic” and “unprecedented” in describing this heat wave, we need to provide some context. Meteorologists at the National Weather Service spent the day pouring through records to do just that.
This is what they found.
This heat wave is not the longest, and it’s not even close to being the hottest. However, it may be one of the most uncomfortable and dangerous heat waves in terms of the combination of heat and humidity.
The closest matches are the heat wave of 1980, which claimed more than 150 lives, and the heat wave of 1995, which holds the record for the highest-ever recorded heat index at 120. The summer of 2012 had numerous 100-degree days and was a totally different type of heat wave, according to Ben Herzog of the National Weather Service.
“One part about 2012, we were in a drought. We were very dry, and that was a much drier heat,” Herzog said. “Our temperatures were quite a bit higher than what we are seeing right now, but our heat indexes were not nearly what we are seeing right now. So definitely a very different set-up.”
In fact, it was so dry in 2012, that the heat index was lower than the air temperature at times.
Since the National Weather Service began tracking dew points and, by default, the heat index, there have been 7,076 summer days. Out of all those days of summer, only 15 recorded a heat index of 115 – three of which occurred in 2023! If the forecast plays out, our string of 115-degree heat index days will reach 5 for only the second time since 1946! Our three consecutive days of 80+ degree dew points are the most on record!