running in humidity chart

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Enter in the air temperature (Tair) in degrees Fahrenheit and relative humidity (RH) in percent (without the % sign), then click on the Calculate HI to compute the heat index (HI) | Use the heat index tables
OR use dew point temperature
Heat Index CalculationHeat Index Calculation
Enter in the air temperature (Tair) in degrees Fahrenheit and relative humidity (RH) in percent (without the % sign), then click on the Calculate HI to compute the heat index (HI) | Use the heat index tables
OR use dew point temperature

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Dew point running- what is dew point?

The dew point is the temperature below which water droplets condensate, and due forms.

You might be familiar with dew point in reference to when water droplets form on grass and flowers in the morning.

But did you know that the same thing happens with humans?

And it’s a more reliable measure than humidity. The higher the dew point, the more water droplets (or sweat) form on our skin.

Why is it harder to run in humidity?

More moisture in the air means sweat has nowhere t

More moisture in the air means sweat has nowhere to go

It’s like running into a wall of moisture. Breathing is harder in higher humidity as you are taking in more moisture as a larger component of the air. The oxygen quantity is constant, but when it’s humid, more moisture takes up the space between air molecules.

The air is less permeable for heat to escape and gets trapped longer between molecules. This is why it feels much warmer when there is high humidity.

When humidity is high, the air is full of moisture and sweating doesn’t cool you down efficiently. This is because there is much lesser air molecule real estate for sweat to evaporate into.

When we run, we sweat a lot. When our bodies start to heat up, our sweat glands are working hard throughout our body to cool us down. It makes our skin feel cooler and removes heat from our bodies when it evaporates.

“When internal temperature rises, the eccrine glands secrete water to the skin surface, where heat is removed by evaporation.”

Humidity makes running more uncomfortable when sweat cannot evaporate fast from our bodies and not allowing us to cool by dissipating heat. It slows your running down because your body is working to prevent overheating. When the sweat has nowhere to go, your skin turns sticky.

The higher the humidity, the harder the body works to keep cool

The body’s natural cooling system simply can’t keep up. Sweat will take forever to evaporate and the body heats up. With increased humidity, the heart rate will also increase as it is working harder to keep cool. It can increase up to 10 bpm in 50%-70% humidity and up to 30bpm in 70%-90% humidity.

The body burns more energy as it is working harder to cool off. This also means you will deplete carbohydrate stores faster than usual and you are more likely to be at risk of overheating or heat exhaustion because the body is working overtime to cool off in the saturated air.

The hotter your body gets, the more blood your heart needs to pump to your skin to dispel that heat. Even in lower temperatures, high humidity can affect your heart rate and your body temperature can keep rising. This means your easy run pace may become much harder.

Your tech shirt becomes useless at regulating temperature – Backed by experiment results

In a documentary aired by Channel News Asia, an experiment was conducted in Singapore, where humidity is well over 80% most of the time.

A pair of twins ingested microsensors to measure the core temperature when running. One wore a tech tee and the other an ordinary cotton tee. How effective was the tech tee at regulating temperature? The two screenshots show there is not much difference.

Screenshot from ChannelNewsAsia Documentary Why It
Screenshot from ChannelNewsAsia Documentary Why It Matters 2: Killer Heat

The trend of core temperature results seems pretty consistent given the variables were the same except for the shirt.

Screenshot from ChannelNewsAsia Documentary Why It
Screenshot from ChannelNewsAsia Documentary Why It Matters 2: Killer Heat

We are of the impression tech tees are better at wicking moisture and bringing sweat to the surface of the shirt so that it can evaporate faster and disburse heat. There is nothing wrong with that concept.

It’s just that in high humidity, the benefits may be negated as explained in the video.

You can check out the documentary here. (opens in a new tab)

Race Equivalency Conversion Calculator – How It Works?

A Race Equivalency Calculator converts raw finish times from races you have run into virtual performances, if you will, that are comparable to performances from other races and even of other runners. At the most basic level, this tool allows you to determine whether you are getting better or worse over time.

To ensure the race equivalency and conversion calculator provides the most precise calculation you’ve got to make sure environmental factors such as weather, topography, and the overall continuity of both races are on par with each other.

Likewise, if during your last race, your finish time was slower than your previous race’s finish time, this probably means you should spend more time improving your running technique or maybe try a new running and exercise routine. Or, if in a previous race, then you’ll know that you’re trending in the wrong direction.

By looking at your previous times, you can try to figure out whether or not you are going faster or just getting slower. Also, here’s what the race conversion calculator as designed by Pete Riegel looks like.

T2 = T1 x (D2 / D1)1.06 T1 = the time achieved recently on distance D1 T2 = the predicted time for distance D2 D2 = the distance over which T1 time was achieved D2 = The distance for which T2 time is foreseen.

Essentially, what Riegel’s race equivalency calculator is doing is telling us what to expect in an upcoming race based on how you performed in a prior race.

READ   Best Core Exercises For Runners to Improve Performance

So, if you’d already clocked a half marathon time of 1hr 50min (110 minutes) but was curious how you might perform in the full marathon, here’s how you’d calculate it.

T2 = 110 x (26.2/13.1)1.06 = 233 min = 3hrs 53min



Medical issues you should know about

Medical issues when running in high humidity

Medical issues when running in high humidity

High humidity can contribute to feelings of perceived higher fatigue, low energy, and lethargy. This is because when your body works overtime to cool you down, it actually heats up. It’s no different from the condenser in your air conditioning system.

It also leads to two main problems. Dehydration and overheating.

It’s a nasty combination. In extreme cases, when the brain decides the body is way overheated, it diverts more blood to the heart and lungs, going into survival mode. Deprived of blood, your digestion system cannot process nutrition and will reject it by making you throw up.


“Dehydration is a condition that can occur when the loss of body fluids, mostly water, exceeds the amount that is taken in. With dehydration, more water is moving out of individual cells and then out of the body than the amount of water that is taken in through drinking.”

In a humid environment, it’s not surprising that dehydration is a problem. An average person can sweat anywhere from 0.5-2 liters for each hour of exercise. That’s above the capacity of 1-4 small coke bottles.

So imagine if you were doing a long run for 2-3 hours to train for a marathon. It gives us a good indicator of how much water we need to prevent dehydration.


Overheating can cause decreased muscle endurance, which means the muscle’s ability to expand and contract repeatedly to sustained movement over long periods of time is greatly diminished. The body cannot keep up with the requirements of the evaporation of water from your skin. Overheating can manifest in the conditions below.


This warrants immediate medical attention. It is extremely serious and is a life-threatening condition. Symptoms include a body temperature of 105° F or higher, dry/hot/flushed skin, disorientation, and nausea.

Cardiac Drift

This refers to the increase in heart rate where there is no change in workload. The heart rate goes up when the activity performed should actually decrease the heart rate. This is anchored in the concept that the heart rate reflects the intensity of the work performed.

Heat Cramps

Acute muscle contractions caused by fluid and electrolyte losses. Water, salt tablets and electrolytes should do the trick in relieving this.

Heat Exhaustion

Symptoms include dehydration, nausea, headache, and an increase in temperature over 100° F. You need to stop running immediately and get to cooler temperatures before it manifests itself as heat stroke.

Medical issues when running in low humidity

Humidity that’s too low (30 and below) can cause a different set of problems. Low humidity causes dry skin, irritates your nasal passages, and makes your eyes itchy. As skin is over half water. air that is too dry can cause flare-ups of eczema and acne. This can also cause itching, flaking, and tightness around the joints

The throat and nose are lined with moist membranes. These membranes filter out foreign particles such as viruses and dust before they enter the lungs. When these membranes lose moisture due to low humidity, their abilities to filter particles is diminished.

Low humidity levels can cause the inside of the nose to become dry and irritated. This is not only painful, but it can also cause nosebleeds.

Long periods of exposure to low humidity can dry out the mucous membrane that lines your nose and throat, This increases the risk of inflammation, catching viruses from the common cold to influenza and other infectious diseases.

So the obvious solution is to stay hydrated. Keep drinking at regular intervals and you should be fine. This is also why practicing your nutrition plan during training runs is so important.

How to cope with running in high dew point

A high dew point doesn’t need to knock you off your training. You can train through it using the following 5 techniques.

  • Plan your route to be through shaded areas. Think through the woods, or down narrow streets.
  • Wear technical, sweat-wicking running clothes. This will mean that your clothes won’t stick cling to your skin as much.
  • Wear a running hat soaked in cold water or filled with ice. This will keep you cool for obvious reasons, it feels great!
  • Drink more fluids per hour. You will inevitably sweat more. Stay safe and hydrated!
  • Adjust your pacing targets. It is good to be mentally prepared for your slower pace. Just remember you’re not getting worse at running, it’s just the weather!

Problems with Humidity that is Too High

What is considered high humidity? Anything above 50% can be too high in cold weather, but definitely above 60% regardless of the weather.

It’s been known for some time and verified with Covid-19 that high humidity slows the spread of viruses, especially coupled with higher heat. That’s fine for a relaxing steam shower, but not for your entire home. In general, high humidity brings more problems than solutions.

Here are concerns with humidity above 50% to 60%:

1). Promotes the growth of mold, mildew and bacteria – and allows them to spread more easily.

Usually these issues are seen when humidity is higher than 60%, but there are scenarios where mold can begin to grow when humidity is as low as 40% to 45%.

For example, if your walls are poorly insulated, and a very cold wind is blowing against one of them, the interior of the wall – and even the inside surface of the wall – can get cold enough to condense moisture even if the indoor humidity is 40%. And when moisture and mold spores mix, mold grows and spreads.

2). Mold spores in the air cause more than a musty odor. They can cause illness and make existing illnesses worse. The last thing someone with heart disease needs is mold in their lungs, making it harder to breath and get oxygen into their blood. That’s just one serious example.

3). High humidity makes asthma and allergy symptoms worse.

4). Moisture can rot the framing of your home. Roofing, flooring and general contractors commonly find rot when renovating homes. Sometimes a leaky roof or pipe is the cause – but often it is high humidity levels getting into wood framing and subflooring to cause the damage.

5). High humidity makes a room feel clammy or sticky. In cool weather, or when you have the AC running but it’s not dehumidifying very well, the air is cool and clammy. When it’s warm and humid, the air gets “close.” Neither is comfortable.

6). Higher cooling bills. In warm weather, humid air is less comfortable – as just stated. The normal inclination is to turn down the thermostat and crank up the AC. This might make you more comfortable – until you get the higher electricity bill.

Solutions to Humidity that is Too High

The best way to bring down humidity that is too high include:

  • Sealing your home, replacing old doors and windows and upgrading house wrap – just as discussed when dealing with humidity that is too low. The key is to create a tighter envelope, and when you do, it is much easier to control the humidity indoors.
  • Installing a dehumidifier in your home to remove excess moisture.
  • Upgrading your central air conditioner to a two-stage or variable capacity model. These units remove more moisture than older single-stage
  • If you’re shopping for a window AC, consider one that has Dry Mode. It basically turns the unit into a dehumidifier. The heat is taken out of the air but returned to it, so the room doesn’t cool off. However, the moisture removed from the air in the process is drained outside, lowering the humidity level indoors.

See the Window Air Conditioner tab or the Portable Air Conditioner tab at the top if you’re interested in finding a window AC or portable unit with Dry Mode. They’re available in many sizes – you’ll find some in the Best 15000 BTU Window ACs Guide, for example, plus in the Quietest Portable AC Guide too.

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