I saw a post on /r a couple of days ago that said that a sizeable region of the US was currently in a 'killer' combination of temperature & humidity ranges ...and we'd better get used to it as it is going to get worse. The sentence that caught my eye was that at 94f & 70% RH you can die without air conditioning. The temp & Rh combo is measured as Wet Bulb Globe Temperature which we've mentioned here before. Being from the Southeastern coast, 94f & 70% is pretty much our average July & August, so I thought that seemed low and went on a quick-study search. Nope, the post was right (though it didn't mention that it can also take into account other factors such as Full Sun and Breeze).
Here's a chart:
https://arielschecklist.com/wbgt-chart/
> 94f & 70% RH
It is 94F & 60% RH here now.
Record-breaking Heat in the Summer of 2022 Caused more than 61,000 Deaths in Europe - Barcelona Institute for Global Health
https://www.isglobal.org/en/-/el-calor-record-del-verano-de-2022-causo-mas-de-61-000-muertes-en-europa
Have you read Kim Stanley Robinson's Ministry of the Future? I haven't read it, but as I understand, the opening is about a severe wet bulb event in India. I read a comment by him where he said when he was writing the book, he was afraid people might not believe it, but he never imagined there would be a serious wet bulb event in CANADA within a couple years (maybe the same year) as publication.
Lots of hot humid places will be in the summer similar to the super cold places in the winter (i.e. limited time outside before bad things happen; death to many if the power goes out; many deaths for poor and unsheltered people).
In the US, the National Weather Service is quietly (anti-science & politics) rolling out a WBGT forecast. Try tacking /wbgt on the url of your regional weather center. A quick check turns up some regions that don't have it yet or maybe they're using a different url suntax. Here's mine;
https://www.weather.gov/akq/wbgt
But it is not very granular, so I went looking. The chart posted above works, but -hell- this is the 21st century and we have the internet. We can do better than charts --particularly when it comes to forecasting.
WBGT is a big deal already in athletic events. UNC built a tool that seems to be widely used.
UNC's Wet Bulb Globe Temperature (WBGT) Tool - Convergence of Climate-Health-Vulnerabilities
https://convergence.unc.edu/tools/wbgt/
I use the lat/lon of my house and set in on NC High School athletics. That should cover any sort of outdoor project homeowners have. It did flag a 1-hr "black" period a day or two ago which I verified with local temp & RH on my household weather monitor.
And here's the NWS experimental page;
National Weather Service - Graphical Forecast
https://digital.mdl.nws.noaa.gov/?zoom=4&lat=37&lon=-96.5&layers=F000BTTTFFTT®ion=0&element=8&mxmz=false&barbs=false&subl=TFFFFF&units=english&wunits=nautical&coords=latlon&tunits=localt
>> athletic events
I can only imagine summer football leagues in inland NC.
I went for a run recently in Minnesota (yes, you can sneer derisively at me) and at first I felt so fast because of the thick air and all that oxygen. But by the six-mile mark I was worn down by the heat and humidity. My body was drenched and even my feet were hot. I don't think it was even 80 degrees. Definitely not 85. It was late afternoon so little direct sun. Oh and I was shirtless.
I can't imagine NC in full sun and football gear in August. Now that you bring it to my attention, I foresee a lot more indoor stadiums even at the high school level.
For every problem, there's a business opportunity
WBGT monitor that can be programmed to send SMS and other alerts based on protocols like the ones available in the tool you linked (e.g. ret every 20 minutes).
https://perryweather.com/features/
Census Bureau: Almost a Quarter of U.S. Population Vulnerable to Rising Heat
https://www.census.gov/library/stories/2023/07/almost-a-quarter-of-population-vulnerable-to-rising-heat.html
Why you need to worry about the 'wet-bulb temperature' | Climate science | The Guardian
https://www.theguardian.com/science/2022/jul/31/why-you-need-to-worry-about-the-wet-bulb-temperature
How To Survive A Wet Bulb Event | Hackaday
https://hackaday.com/2023/07/27/how-to-survive-a-wet-bulb-event/