Question about humidity

Psymonds

DIS Veteran
Joined
Feb 21, 2006
Messages
667
Coming from California, and having been there just now in July, I'm wondering how the heat index/humidity compares for the marathon weekend. I'm interested in 2025 (just doing halfs this year) but I'm not sure I won't wilt coming out from our dry heat. Any other runners prep in dry environments and run the January weekend and have experience?
 
Normally the humidity in Florida in January is pretty mild. Lived there for over 10 years and I honestly can't remember a time when it was hot and humid and sticky between December and January. The average temp is apparently between 51 and 72, so just beautiful!

Stranger things have happened, but you should he okay (especially considering the time of day).
 
Coming from California, and having been there just now in July, I'm wondering how the heat index/humidity compares for the marathon weekend. I'm interested in 2025 (just doing halfs this year) but I'm not sure I won't wilt coming out from our dry heat. Any other runners prep in dry environments and run the January weekend and have experience?

I'm from the northeast so I'm coming from a cold and dry (at least that time of year) climate.

People may say that January isn't humid - and it isn't compared to Florida summers - but I've struggled with the humidity nonetheless, even on the cooler mornings. The key for me is to hydration. I carry my own water as I don't find the race water enough on the shorter races, particularly the 10Ks. I can also use that water to soak my shoulders and neck if I start getting warm and/or sweaty. I'm also very conscious of pre-hydrating in advance of the races, immediately after the races (I aim to finish my finish line water bottle before I get back to my hotel) and over the course of the weekend.

There are some methods for heat acclimation. I've used the hot tub and the steam room at the gym in the past. I don't know how much it helped, but at least it was something.
 
I'm from MN and I've only done one Marathon Weekend (2023) but I have done several January WDW visits and weather is a total gamble. It's nothing like FL summer of course, but you can still have extremely sticky mornings and you can have relatively dry mornings. No matter what it will feel much stickier than you probably get in CA, but it can range from not a big deal to being sweatier than in your life between two days. Mainly I recommend hydrating as much as you can, I also like drinking electrolytes in the days leading up and during the longer races as well like nuun or tailwind or gatorade, etc. Slowing down too, I find the humidity makes it harder for me to breathe.

For MW this year the 5K was the most sweaty I have gotten on a run in my entire life! I want to say it was 70-80 but it was like 90-100% humidity (the early race starts mean peak humidity) and within a mile I was already drenched. My race photos are so funny because I look like I ran a marathon, and all I did was a slow 5k.

Meanwhile the marathon a few days later was quite dry and much cooler, no heavy/sticky feeling at all even at 3AM and I hardly broke a sweat during the entire race! I'll take a sticky, gross 5k any day for 2023 marathon weather again!

I will say I find temperature is a much bigger indicator of misery in FL than the actual humidity %, I think it was pretty humid during the half but because it was so cold (45-50), I didn't really notice it at all other than the fog. I'd say the high humidity only starts getting problematic when it gets closer to high 60s and up. People smarter than me can talk all about adding the dew point + temperature to better measure that but all I know is that anything over 70 degrees by 5AM gets me very nervous in FL, no matter the humidity % :laughing:
 
I'm from MN and I've only done one Marathon Weekend (2023) but I have done several January WDW visits and weather is a total gamble. It's nothing like FL summer of course, but you can still have extremely sticky mornings and you can have relatively dry mornings. No matter what it will feel much stickier than you probably get in CA, but it can range from not a big deal to being sweatier than in your life between two days. Mainly I recommend hydrating as much as you can, I also like drinking electrolytes in the days leading up and during the longer races as well like nuun or tailwind or gatorade, etc. Slowing down too, I find the humidity makes it harder for me to breathe.

For MW this year the 5K was the most sweaty I have gotten on a run in my entire life! I want to say it was 70-80 but it was like 90-100% humidity (the early race starts mean peak humidity) and within a mile I was already drenched. My race photos are so funny because I look like I ran a marathon, and all I did was a slow 5k.

Meanwhile the marathon a few days later was quite dry and much cooler, no heavy/sticky feeling at all even at 3AM and I hardly broke a sweat during the entire race! I'll take a sticky, gross 5k any day for 2023 marathon weather again!

I will say I find temperature is a much bigger indicator of misery in FL than the actual humidity %, I think it was pretty humid during the half but because it was so cold (45-50), I didn't really notice it at all other than the fog. I'd say the high humidity only starts getting problematic when it gets closer to high 60s and up. People smarter than me can talk all about adding the dew point + temperature to better measure that but all I know is that anything over 70 degrees by 5AM gets me very nervous in FL, no matter the humidity % :laughing:
yeah absolute humidity is temperature dependent, the percentage reported is the "relative humidity" but dewpoint is a good indicator of absolute humidity. needless to say I am a little concerned and I might need to heat condition some. (since even here I tend to run early to avoid the 80-90 degree temperatures)
 
When I head to MW, I'm coming from northern Michigan in the winter, and it's DRY from a humidity standpoint. I will echo what others have said about hydration and electrolytes (I try to get on top of my hydration at least a week ahead of time, and extra electrolytes a few days leading up to the races.) Also, whatever anti-chafe stuff you use. Know where your "hot spots" are and apply stuff as a preventative on race morning. Consider carrying a travel-size stick of something if you are someone who chafes easily.

Otherwise, just slow down and have fun. IME, the mornings start out "damp" but generally cool, and the humidity burns off some once the sun comes up. But the temperatures in January can be 40 or 80, and we won't know until possibly the day before the race, even though we all stalk the weather forecast as soon as it'll show up on websites. :crazy: This is where throw-away layers work well, and Disney launders and donates all clothing that is ditched along the course. I ran the first 7 or so miles of the marathon with a long-sleeve tee over my costume this year, and was sweating almost immediately in 2022.
 
When was the last race they shortened from the heat? With how godawful it's been here in HTX this year I'm not sure I'd complete a marathon in these conditions. It's been 82F with a dewpoint of 81F every morning for weeks.
 
I believe it was the 2020 marathon that was cut short. My memory sucks so don’t hold me to that 😂

I live near WDW. Weather here can be 25 or 85 in January and it is humid year round. The races will start out cold & wet, warm & wet, hot & wet or any combination of the three. Watch the weather and pack for all temps.
 
I believe it was the 2020 marathon that was cut short. My memory sucks so don’t hold me to that 😂

I live near WDW. Weather here can be 25 or 85 in January and it is humid year round. The races will start out cold & wet, warm & wet, hot & wet or any combination of the three. Watch the weather and pack for all temps.
I think you’re right about 2020. BB loop cut off for folks who hadn’t gotten there, IIRC around 11:00.
 
2016 marathon was only 71 (starting temp and maybe dropped a couple during race), but it was all the humidity. I’m used to humidity here, but you’re not going to find a lot of it in most states during your peak training months of Nov/Dec.
 
I believe it was the 2020 marathon that was cut short. My memory sucks so don’t hold me to that 😂

I live near WDW. Weather here can be 25 or 85 in January and it is humid year round. The races will start out cold & wet, warm & wet, hot & wet or any combination of the three. Watch the weather and pack for all temps.

For 2020, the official race start temp was 70 degrees and 94% humidity, with temps going up to 87 by noon. My watch said it was around 74 degrees at 5 am, and it was a tough run and a rough scene. Just as I reached the 26-mile marker, I saw a woman being assisted off the course by medics. You could see the finish line—I felt so bad for her!

 
For 2020, the official race start temp was 70 degrees and 94% humidity, with temps going up to 87 by noon. My watch said it was around 74 degrees at 5 am, and it was a tough run and a rough scene. Just as I reached the 26-mile marker, I saw a woman being assisted off the course by medics. You could see the finish line—I felt so bad for her!

I have a co-worker who has twice ended up in the medical tent in the last mile of an ironman. I feel for that lady too.
 
Old post, but relevant:

I use something like this to get a general view of what Orlando weather is like during the time and dates of Marathon Weekend.

Screen Shot 2022-12-21 at 1.13.48 PM.png


The above system uses T+D which is Temperature + Dew Point. While not perfect, it is a good way to compare different conditions across different temps/humidity levels. The higher the T+D value, the worse the conditions. And the typical response is not linear. So a 160 is much worse than a 155 than a 110 vs 105.

And it agrees with the local FL residents. The weather tends to be very unpredictable in FL at this time of year. You have a nearly even chance of ideal, good, ok, not great, and bad weather. You can also see examples of weather turning from "ideal" to "bad" within a two-day span in a single year. So the 5k could have "ideal" weather and the half marathon "bad" weather and it wouldn't be all that surprising. The one trend I do see in the eleven years of data is that as it goes from Jan 6th to Jan 12th we see more "ideal" days shift to more "bad" days. Jan 6th has 7/11 ideal or good, Jan 8th has 5/10, Jan 10th has 4/11, and Jan 12th has 2/11. With the races occurring Jan 4th-7th in 2024, the chances are higher that there will be "ideal" conditions versus "bad". But that's only the chance and certainly not definitive. I haven't looked, but 2025 might shift to a later calendar with MLK Day on Jan 20th meaning worse average conditions.
 
Last edited:
Old post, but relevant:

I use something like this to get a general view of what Orlando weather is like during the time and dates of Marathon Weekend.

Screen Shot 2022-12-21 at 1.13.48 PM.png


The above system uses T+D which is Temperature + Dew Point. While not perfect, it is a good way to compare different conditions across different temps/humidity levels. The higher the T+D value, the worse the conditions. And the typical response is not linear. So a 160 is much worse than a 155 than a 110 vs 105.

And it agrees with the local FL residents. The weather tends to be very unpredictable in FL at this time of year. You have a nearly even chance of ideal, good, ok, not great, and bad weather. You can also see examples of weather turning from "ideal" to "bad" within a two-day span in a single year. So the 5k could have "ideal" weather and the half marathon "bad" weather and it wouldn't be all that surprising. The one trend I do see in the eleven years of data is that as it goes from Jan 6th to Jan 12th we see more "ideal" days shift to more "bad" days. Jan 6th has 7/11 ideal or good, Jan 8th has 5/10, Jan 10th has 4/11, and Jan 12th has 2/11. With the races occurring Jan 4th-7th in 2024, the chances are higher that there will be "ideal" conditions versus "bad". But that's only the chance and certainly not definitive. I haven't looked, but 2025 might shift to a later calendar with MLK Day on Jan 20th meaning worse average conditions.
this is a very useful way to think about it, and I'd always looked at dewpoint as more intuitive for humidity because "relative" humidity is, well, relative, we'll be at 100% humidity here a bunch in the SF area but, always at the low end of the temperature scale.

it appears the short answer is, it could be good, but it just as likely could be moderate to bad... I'll have to just be ready to adjust to what my body can handle and be ready with hydration.
 
OK, training through summer/fall in California. Definitely doing some of my training in the afternoons to simulate heat.

maximum t+D I've been able to pull has been 137. so looking at the chart history, I might experience 140-150 but it might be 120 or below.

As long as we stay hot I'll keep trying to heat condition in the 130 plus days. (fortunately or unfortunately we were out in the mountains when it was 140-150 here in july).
 
OK, training through summer/fall in California. Definitely doing some of my training in the afternoons to simulate heat.

maximum t+D I've been able to pull has been 137. so looking at the chart history, I might experience 140-150 but it might be 120 or below.

As long as we stay hot I'll keep trying to heat condition in the 130 plus days. (fortunately or unfortunately we were out in the mountains when it was 140-150 here in july).

In reference to training for 2025 MW, the current training you're doing in warmer temps will be advantageous from a mental standpoint. You'll learn to adjust pace by effort given the changing temps you're experiencing. But unless the temps persist from now through December, then you'll likely lose the physical adaptations far earlier than MW. It takes about 10 days to 2 weeks to start to see acclimatization to warmer temps, and you'll just as soon lose those adaptations in a similar timeframe. But as I posted in the MW thread, the odds of a higher temp marathon are higher than the odds for an ideal weather one based on historical data on Jan 12th. So being prepared mentally is a good thing. There was some recent research that I saw a few years ago about acclimation using a hot tub in the few weeks prior to the event, but haven't followed it up to see if it's been disproven yet. I'm a personal fan of overdressing for the last few weeks ahead of the event, and my personal collected data bores out that my body has improved acclimation to warm temps despite coming from WI winters (as low as -50F).
 
In reference to training for 2025 MW, the current training you're doing in warmer temps will be advantageous from a mental standpoint. You'll learn to adjust pace by effort given the changing temps you're experiencing. But unless the temps persist from now through December, then you'll likely lose the physical adaptations far earlier than MW. It takes about 10 days to 2 weeks to start to see acclimatization to warmer temps, and you'll just as soon lose those adaptations in a similar timeframe. But as I posted in the MW thread, the odds of a higher temp marathon are higher than the odds for an ideal weather one based on historical data on Jan 12th. So being prepared mentally is a good thing. There was some recent research that I saw a few years ago about acclimation using a hot tub in the few weeks prior to the event, but haven't followed it up to see if it's been disproven yet. I'm a personal fan of overdressing for the last few weeks ahead of the event, and my personal collected data bores out that my body has improved acclimation to warm temps despite coming from WI winters (as low as -50F).
I think the mental fitness is worthwhile. I certainly have overcome the "I can't go running it's 85 or 90 out" feeling and have learned to prepare/hydrate for warmer runs.

we *might* get some 80 degree days into November but won't be sniffing that in December... we don't have a hot tub either (and the community pool closes in oct).

this is good info.
 
I think the mental fitness is worthwhile. I certainly have overcome the "I can't go running it's 85 or 90 out" feeling and have learned to prepare/hydrate for warmer runs.

we *might* get some 80 degree days into November but won't be sniffing that in December... we don't have a hot tub either (and the community pool closes in oct).

this is good info.

A Florida heat of 85 is very different from a mountain west heat of 85 (I’ve run in both). I don’t think any form of “heat training” can prepare a northerner for the pure swampiness of 99% humidity. I know people train for the Badwater ultra by running in place in a sauna or on a treadmill next to a dryer with the exhaust hose blasting at them. But the Florida humidity is deceiving, because if the weather is cooler, it doesn’t seem that bad at first. But your body can’t cool off by evaporating the sweat, and suddenly your core is overheating and everything sucks and the run now feels 1000x harder. I find running in humidity much more mentally taxing because a pace that felt easy at first quickly becomes a slog.
 












Save Up to 30% on Rooms at Walt Disney World!

Save up to 30% on rooms at select Disney Resorts Collection hotels when you stay 5 consecutive nights or longer in late summer and early fall. Plus, enjoy other savings for shorter stays.This offer is valid for stays most nights from August 1 to October 11, 2025.
CLICK HERE









DIS Facebook DIS youtube DIS Instagram DIS Pinterest

Back
Top