So how humid is it? It’s stinkin’ humid.
Dewpoints are in the 70s. At one point Friday, the dewpoint was a steamy 76ºF at Huntsville International, and it was that thick moisture that made it feel so much hotter outside. The heat index was over 100ºF as actual air temperatures hovered in the upper 80s and lower 90s.
This tropical air isn’t going anywhere. Get used to it.
Dewpoints this high will make it feel a lot hotter than the thermometer indicates through early next week!
So how does this make it ‘feel’ so much hotter?
It’s all about how your body naturally cools itself: sweat.
Remember the water cycle from elementary school? Evaporation, condensation, precipitation?
Sweating to keep cool is a cousin of the water cycle in natural science. Your body produces sweat (like water), that sweat absorbs heat from your body radiating out through your skin. When it absorbs enough heat energy, it will evaporate: taking the heat away from your body providing a net cooling effect.
Here’s the problem: evaporation requires ‘dry’ air in the space around the water. The more water vapor (humidity) there is in the air, the less effective the evaporation process becomes, and that leaves you hotter and wetter because the sweat ends up hanging around instead of joining the air as water vapor.
Now, your body temperature is starting to rise (you’re getting a fever) because you can’t cool down. Your body is using up water quickly producing more and more sweat, and you’re not getting any cooler. That can lead to heat exhaustion or even heat stroke.
The highest temperature so far in 2019 at Huntsville International Airport was 98ºF on July 9th. In Muscle Shoals, it was 98ºF on May 26th.
The hot weather setting up from Sunday to Tuesday could get us close to that kind of heat again, but this time, the thick, tropical humidity means this time the heat index will be higher.
There’s a mindset out there that ‘heat index’ and ‘feels like’ temperatures are ‘fake news’ these days. Ignore the warning at your own peril; this is nasty and dangerous kind of heat whether you’re in good health or not. It’s not dangerous to simply be outside; it’s dangerous when you are overworking yourself, not staying hydrated, etc. Just use common sense. Send your football players and band members to practice with water and impress upon them the importance of listening to the leaders when it’s time to take a break.