Ran in 80F with 55F dew point vs 80F with 75F dew point - what a difference!

trhjdsr wrote:

After a summer of high temperatures and high humidity (about 72-75F all summer) today was the first day of 80F with a dew point lower than 60F (the upper comfortable limit) . The main differences are the effort and the sweat! I timed myself on a flat 5 mile path and I was able to run it 5% faster with about 75% of the effort than with high humidity. In the shade the air was pleasantly cool. The sweat on my body was minimal. In high humidity I finish with a glassy, sticky torso. I am so wiped out. With low humidity I could keep on running. Life is good with low humidity. Life is not good with humidity.

Agree. It was nice and makes a huge difference.

Yes, indeed. Humidity sucks.

Today was also the first day for me were running was easy and fun.

I don't need more cheap t-shirts wrote:

Yes, indeed. Humidity sucks.

Today was also the first day for me were running was easy and fun.

Same here. Best running weather day since June. Most mornings the last 2 months have been in the 72-75 range. It was nice to come home not completely drenched.

"Dew point isn't a measure of humidity,"

Dew point, for most people, is a measure of comfort:

Less than 60F is comfortable. More than 65F is humid. More than 70F is uncomfortable. More than 75F is miserable.

Dew point can never exceed air temperature (sometimes however it is indicated 1F degree over) and with that and temperature you can figure the relative humidity, which is only relative. Look to dew point for how you will feel.

Glad to hear the heat is breaking in some places. Long runs have been leaving me on the verge of dangerous dehydration.

I always go by the dew point and the temperature, and rarely even look at the relative humidity.

Indeed! We had a nice week too after horrible heat and humidity, felt so good ended up running a fast tempo at almost 10k race effort

Unfortunately tomorrow it's forecasted to get to 114F

The bigger the gap between temperature and dew point, the easier it is for sweat to evaporate, thereby cooling you. That's the short of it.

To say that under 60 dew point is always comfortable is not quite right either. For instance, if it's 58 F and the dew point is 52 F, you will find yourself saturated in sweat with a hard effort because the air is nearly saturated with water and there is no where for the sweat to evaporate too. Now the fact that the actual temperature is low helps offset the lack of evaporative cooling.

There are three pieces of info to consider ... intensity of the sun, absolute temperature, dew point. I ran a marathon in Utah several years ago where the temperature was like 50F at the start and the dew point was non-existent. Sounds great, right? Well it wasn't, because there were also no clouds and the intensity of the sun really started to be a problem two hours in.

One thing to be aware of is if there is a huge gap between temperature and dew point, you will never have sweat on you, or very little, and it's easy to get dehydrated because you can't tell how much sweat you're producing. It evaporates that fast.

Great. It s been months that we have not been below 80...we ll never reach 60 anyway...but...different country.

This weekend has been great. I live in the DC area and the summers here are really humid. We had a stretch of over 50 days where the overnight lows were not below 71 degrees but lately, and especially this weekend, lows were around 60. Running is much more enjoyable.

At the end of June I went out west to Salt Lake and some National Parks. One day I ran when it was 92 but the dew point was very low and it felt great. Shorts weren't even soaked. In Flagstaff it felt very comfortable to run even though it was at elevation. It's much more uncomfortable to run in humidity than at elevation.

Yeah, running in NC this summer has been brutal. Everyday has a dew point above 75-80F, which is no exaggeration. Yesterday I went on a run and it was quite literally heaven, escaping from that insane heat + humidity + dew point combo is so nice. As a hs runner, running after school has lent itself to some insane weather combos.