One of the things that makes the heat so dangerous here in Florida is the humidity. The dew point temperature is the temperature at which the air can no longer hold all of its water vapor, and some of the water vapor must condense into liquid water. At 100% relative humidity, the dew point temperature and the air temperature are the same, and clouds or fog can begin to form. While relative humidity is a relative measure of how humid it is, the dew point temperature is an absolute measure of how much water vapor is in the air (how humid it is). In very warm, humid conditions, the dew point temperature can reach 75 to 77 degrees F, but rarely exceeds 80 degrees.
The dewpoint for the afternoon that caused my heatstroke was between 71f and 74f. The temperature for that 4 hour period was between 91f and 94f. That results in a heat index of between 100f and 103f.
High dewpoints are dangerous because it is a limit on how well your sweat can evaporate and cool your body. Heat can build up to dangerous levels.
Combined with that, it was a bright, sunny day with almost no wind. The Navy actually has tables for permissible heat exposure. Under those conditions, Navy regulations say that acclimatized personnel shouldn’t perform heavy work for more than 15 minutes per hour. I far exceeded that for more than 4 continuous hours.
Even worse, I am now 35 years older than I was when I was in the Navy. I am also about 40 pounds heavier. All of that makes my susceptibility to heat stress more pronounced.
As I said, I know better. Let my experience in this case serve as a warning to others as we enter the hot summer months here in the South.
14 Comments
Gregb · May 21, 2025 at 5:44 am
Just happy you caught it in time. Take care of yourself because nobody else will
oldvet50 · May 21, 2025 at 6:45 am
So glad you’re OK now. I have to question drinking nothing but Gatorade to replenish liquids. I’m no medical expert, but it seems it would increase the concentration of electrolytes in your body without plain water to somewhat dilute them (says the guy that used to take salt tablets in high school, military, etc. during outdoor exercise).
Fred in Texas · May 21, 2025 at 7:21 am
Bad news dude, you are now far more susceptible to heat injuries. But you probably already knew that.
I had a heat injury in August 2010. Fortunately I recognized it and self treated it before it got bad. Unfortunately, it took me years to recover.
Be very proactive at prevention in the future; hydration, electrolytes, take breaks, work in the shade, setup a fan… And don’t panic if you think you’re getting symptoms of heat stress. Just manage the situation. It’ll take a few, to several years to overcome the damage. You probably won’t recover all your heat tolerance. But you’ll be functionally alright in time.
Thanks for sharing your story. A lot of people are absolutely clueless about heat injuries. I’m sure you’ve planted seeds of knowledge in somebody’s mind. It might save their @&$ some day.
Doug · May 21, 2025 at 7:37 am
“A bit dry for some” is just fine for me; “comfortable” is getting too wet. Death Valley in summer is fine. It’s why I’ll never live in or visit Florida again.
Different strokes for different folks (pun intended) 🙂
Tsgt Joe · May 21, 2025 at 8:25 am
Your reports are timely. Today we are cleaning out our old trailer in Okeechobee and taking our stuff to our new place. We are snow birds who ,usually, are back in Michigan May through Christmas. I’ll have to see if I can get electricity to the old place and run the air conditioning. Didn’t handle heat well as a young’n, cant handle it at all at 76. We will probably only work 1 1/2- 2 hours. Dont want to use up Florida medical resources.
Sailor Paul · May 21, 2025 at 5:41 pm
Damn, that is some scary stuff, esp with the delayed reaction.
I had heat stroke in my 30’s. Deeply scary when you realize that you’re alteady truly in a bad place when it happens. The point made about being more susceptible after is fairly made as well. I just refuse to push myself now in the heat.it takes as long as it takes, whatever I am doing.
Glad you’re on the mend and giving yourself time to recover!
Tsgt Joe · May 21, 2025 at 8:28 am
Accidentally hit post before I posted my concern about your health and hopes for your full recovery.
John Fisher · May 21, 2025 at 5:23 pm
Learned some lessons about heat stroke last spring on a golf outing. Got heat exhaustion despite drinking a couple of gallons of water (I carry a 64 oz water bottle and refilled it multiple times). Turns out that the blood pressure medicine I am on (valsartan) depletes electrolytes in some people as a side effect (thanks GP for finding the info). Since then, whenever I’m on the golf course, at the gym or working in the yard, the bottle contains half strength Gatorade mixed from powder. Seems to work.
joe · May 21, 2025 at 6:54 pm
also means you sweat your balls off standing in the shade, that when you get out of the shower and dry off you are already sweating…know all about it living in dfw area…spend an hour mowing the yard and you have to peel your clothes off because they are soaked…
Flashman-7k · May 21, 2025 at 9:13 pm
As a fellow in somewhat the same situation and heavy dewpoints … cheatcode: Tumbler crammed full of nugget ice that you can chew and swallow. Regulate your core temp. It works wonders. When it’s stupid hot, I wear pants with the big cargo pockets and take a couple of the biggest gel freezer packs I can get and put them in the cargo pockets and they work to suck heat out.
If you can have a nearby velocity fan and a seat.
But I probably am not telling you anythingg you don’t know. 😉
McChuck · May 22, 2025 at 5:24 am
Here in NE Midwestia, in winter, the humidity rarely rises above 30%. Nosebleeds are common. In summer, it rarely drops below 50%. Morning fog is common. Whee, what fun.
It’s still better than Florida weather. I had more trouble with heat in Florida than I did in Iraq. The Arizona desert was more comfortable. I don’t miss the cane fields and black muck at all.
TLF · May 22, 2025 at 10:53 am
FWIW, here in GA the state weather stations report the Wet Bulb Globe Temperature (WBGT) index. It adds the impact of sun exposure (the high schools here use it as a guide for football practice in the late summer/early fall). Your conditions in the sun would’ve been code black, no work or practice at all.
Skyler the Weird · May 22, 2025 at 6:08 pm
Had a platoon mate nearly die of heat stroke during a ten mile road march in Category 4 Heat. I had fallen out myself with dizziness and was in the rear taking Gatorade from the medics. He look fine then he vomited and keeled over. We were fanning him and putting ice on him til the medics could get the Ambulance pulled around. He recovered and was out for a few days. I have taken hot days seriously since then.
Exile1981 · May 23, 2025 at 10:18 am
Glad to hear your on the mend. In mid summer we often hit high 30’s (Celsius) outside and occasionally low 40’s. The problem is the boiler house is usually 10 degrees hotter. Add in we have to wear safety gear that is two layers and you have a high risk of heat issues.
The worst is when you have to remove your hear protection to drain out the sweat trapped inside it….
One thing we have is color charts in the bathroom. Basically if your pee is darker than this shade you nust take a break and drink fluids. If its above the darker shade you have to report to the on site medical room.
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