I grew up in the south so the heat and humidity was expected. I mean it is just part of summer right?

We moved to Pennsylvania and got a break from the humidity but picked up a ton of snow instead. I’m not sure which took more of an adjustment.

Photo Jul 04, 9 31 39 AM

Each summer I am quickly reminded of how frustrating and tough heat but especially humidity can be. It single handedly exhausted me during my Chicago Marathon training last summer. I often underestimate just how much it can affect when it comes to running.

There are two main numbers I look at when it comes to humidity before heading out for a run: humidity percentage and dew point.


Dew Point

I’m sure most of you have heard of humidity percentage so let’s start with dew point. This measures the amount of water that is in the air. It is often considered a more accurate measure of how much humidity is in the air on any given day.

For example, Monday morning my husband and I got up to head to the track for him to get in a workout and for me to run roughly 6 miles. We didn’t check the weather as we normally do and headed out to the track. Every step, every mile was so hard. I was dripping sweat about 5 minutes into the run and felt like my entire body was dragging. Putting pregnancy aside, my husband was having a very similar experience and had to dramatically change his workout.

On the way home we finally pulled up the weather and saw that the dew point was 78. The chart below can help you understand what that exactly means when it comes to running:

Dew Point Table


It’s no wonder that run was so hard!


Relative Humidity

Of course, the other common indicator is the relative humidity. Here’s another chart to explain how a percentage increase in humidity can change how the amount of heat feels.



When you are running your body temperature rises and your body’s production of sweat helps to get rid of that excess heat from the body. Humidity comes into play but not allowing the sweat to evaporate off your body. This means that your body can no longer rid itself of the excess body heat.

This obviously came become very dangerous if you aren’t making adjustments, hydrating properly, and cutting back when you need to.

How to Adjust Running for Humidity

Running will have to be adjusted when it comes to extreme humidity. The degree can vary by how much humidity you are dealing with and how your body adjusts. Your body can become adjusted to the humidity to a point, but even that will probably take several weeks.

The important thing is to remember to be patient with your body. Your paces will need to be adjusted during high humidity. This was something that I ignored when training for Chicago last year. Instead of adjusting my paces I kept trying to hit my tempo and speed work paces only to fall short and become extremely frustrated.

Here is a great chart showing how much you should look to adjust your paces based on the humidity:



Don’t try to fight it like I did, but instead make sure to adjust your paces as needed. The effort is still there so you are still putting in the needed work.

If you have a long workout scheduled and notice that you aren’t able to hit the distance, adjust as needed. My husband had planned for a 3 x 2 mile track workout on Monday, but after one round he knew he probably could have done it but the heat and humidity were going to destroy him. Instead he opted to do 12 x 200 meters and a few other intervals to still get in a good workout without destroying his body for the rest of the week.

DO NOT forget your hydration. Your body is losing water even faster and on top of your body already having to deal with the increased humidity, you don’t want it to become dehydrated as well. Carry water with you, even when you don’t think you need it.

I also am more lenient on myself for using the treadmill during the really hot months. I still try to get a majority of the workouts done outside, but if it’s too bad it’s okay to get on the treadmill to get your workout done. The most important thing is effort regardless of if you are out on the roads or on the treadmill.

For the pregnant ladies like myself, make sure to really listen to your body. You can’t let your body get overheated. All the same things are important when you are not pregnant, but you need to be even more cautious and if it’s too hot take your run to the treadmill. Don’t push yourself harder than you need it.  Last Saturday when I was out running it was really humid and hot even though I got out early. I was planning on doing 9 but ended up cutting it a little short around 8. Go out with a plan but be prepared to change and adapt if needed.


The bottom line is humidity can be tough on running. You have to be willing to adjust and focus on effort not specific paces.

Remember, it’s only temporary and it will make you appreciate those fall race temperatures even more.


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