What is considered high humidity outside and at what level?
Humidity levels outside or inside vary depending on the time of day and the season, with summer and winter having high and low levels respectively.
In another article, we asked whether 70 percent humidity is high outside. And we agreed that yes, it is indeed high.
In this post, we shall look at the factors that make humidity level outside to be considered high, and uncomfortable.
Remember, excess humidity has effects on the body, just as much as dry air has serious side effects.
What is considered high humidity outside?
Whether indoor or outdoor, if the humidity level exceeds 55 percent, that is high, if the dew point is high. If the humidity level is between 30 and 55 percent at the right dew point levels, it is considered a good humidity level.
Some people feel more comfortable in relative humidity levels of up to 60 percent. This is not advisable because at 60 percent and above, mold can start to develop in your home.
However, the humidity dynamics indoors can be very different from those affecting the outdoor humidity levels. For instance, outside, there will be wind, and the temperature will not stay constant.
The higher the humidity is, the more saturated with water the air becomes. High humidity outdoors can be very uncomfortable. It can feel really damp on the skin. Besides, air feels warmer at high humidity than it really is.
Unfortunately, the body does not know this feeling of warmth is a false signal. Therefore, it goes into cooling mode, which mainly means sweating. Thus, it is possible to get dehydrated in humid weather.
Dew point and relative humidity
At dew point, the air can no longer hold more water. Thus, it turns into liquid form and falls as rainfall or as fog.
To get to dew point, the air must get to 100 percent RH – relative humidity level. Now, at 100 percent RH, it means that the air is completely saturated with water vapor. It holds all the water it can hold!
Dew point is also defined as the temperature to which air must be cooled to be fully saturated with water vapor.
If you cool the air below this point, the water vapor becomes liquid and forms dew, the same that we find on the grass, plants, windowpanes and other surfaces in the morning.
To simplify this, we can say that dew point is the temperature at which water vapor becomes liquid water.
What is the difference between humidity and dew point?
Higher dewpoint will make the air feel more humid, and vice versa. But it is not that simple. The mechanics are a bit more complex.
If you live in a place such as Florida and you would like to know how damp your day will feel, check the dew point on the hygrometer.
As explained before, dew point is the temperature at which the water vapor condenses to make dew. At this time, we can say that relative humidity is close to 100 percent.
In the article on temperature and humidity relationship chart, we saw that humidity is dependent on temperature. Warmer air can hold more water and vice versa.
Therefore, when we measure relative humidity, it means the percentage of water in the air at a certain temperature.
However, when it comes to the dew point, it depends on the amount of water vapor in the air only and not on temperature. You can use a hygrometer and measure the humidity in the air right now.
Now, if you heat the air and increase its temperature by 11 degrees, the capacity to hold water vapor will double. However, heat can also dry the air. That is why the air in the Sahara Desert is crispy dry, because of heat.
What actually happens is that at 60 degrees, the relative humidity is at 100 percent, which is why you experience increased humidity when it rains.
However, if you increase the temperature of the air, say to 90 degrees Fahrenheit, the humidity will drop hugely to about 33 percent.
Here is a simple chart to show you the relationship between relative humidity and dewpoint:
Outdoor humidity comfort chart
| Temperature | Relative humidity | Dew point |
| 30 degrees Fahrenheit | 100 percent | 30 degrees Fahrenheit |
| 80 degrees Fahrenheit | 50 percent | 60 degrees Fahrenheit |
| 75 degrees Fahrenheit | 50 to 70 percent | 60 degrees Fahrenheit |
| Over 73 percent | Over 80 degrees F | |
| 62 percent | 75 degrees Fahrenheit | |
| 43 percent | 64 degrees Fahrenheit | |
| 36 percent | 59 degrees Fahrenheit | |
| 30 percent | 54 degrees Fahrenheit | |
| Below 30 percent | Below 50 degrees Fahrenheit |
From the above simple table, you can see what how high humidity is affected by temperature. It means:
- When the temperature is at 80 degrees and the relative humidity level is at 50 percent it feels more humid
- When the temperature is 30 degrees and relative humidity is 100 percent, the air feels less humid
- You will also notice that the air feels more humid when the dew point is higher
- You can also tell that dewpoint is a more accurate indication of humidity than relative humidity
What is considered high humidity outside in summer?
Summer months in most places like Seattle, Florida, London, Sydney and others are damp. Therefore, before heading out for the beach, or for work, you might want to know how damp it will feel.
As we said in the previous section, check the dew point on the hygrometer. This is more accurate than the relative humidity level.
If the dew point is less than 55, the day is comfortable, warm and the air is dry. You can engage in strenuous activities such as running, playing soccer or other without the humidity level affecting you.
If the dew point range is between 55 and 65, you will feel the dampness, or the stickiness of the air on your skin. If you engage in strenuous activity, you will sweat gallons. Even if you don’t engage in strenuous activity, you will still sweat.
If the dew point rises above 65, well, that is very high humidity. You will feel the effects of high humidity on your skin, your breathing and your body.
When dewpoint falls too far below 55 degrees, say below 30, the air is going to be very dry. You will experience the effects of dry air on your health if you do not run a humidifier.
An important consideration is that high summer temperature is going to amplify the humidity. Warmer air has a higher capacity for moisture.
What outdoor humidity level is comfortable?
In line with knowing what is considered high humidity outside, you might also want to know what outdoor humidity level is comfortable.
In the indoor spaces, you can control humidity level using the best dehumidifier for basement, or for the bedroom.
Indoors, we recommend keeping the relative humidity level at 30 to 55 percent. That’s comfortable, and okay. High humidity can increase dust mites in the house.
In the outdoor spaces, it can be hard to tame the humidity level. Therefore, all you can do is check your hygrometer and decide whether you can cope with the humidity levels.
Once again, when finding out how damp your day outdoors will feel in summer, refer to the dew point rather than the relative humidity level.
If the dew point level that day is 55 degrees Fahrenheit and below, you are going to have a dry and comfortable day.
When the dewpoint reads higher than 55 degrees Fahrenheit, it’s going to be a damp and sticky day. If it rises above 65 degrees Fahrenheit, it means you will be wallowing in humidity levels approaching 100 percent. There might be fog and/or precipitation.
At 100 percent relative humidity level, the air cannot hold more water vapor, so it expels it as rainfall.
So to answer the question of what outdoor humidity level is comfortable, it is the humidity at the dew point temperature of 55 degrees or below.
Don’t forget that very low dew point means more dry air, which is also not good for you. With that information, you can be able to decide whether to stay indoors or outdoors.
Is 100 humidity dangerous?
100 percent relative humidity is only dangerous if the dew point is high, because then, it could be unbearably hot and damp.
When you are thinking of high humidity levels outdoors or indoors, you must also think about the temperature (in this case – the dew point).
Now, at 100 percent relative humidity, the air is saturated with water to the limit. It cannot hold any more! Therefore, it might, or might not rain.
For rain to fall, the water vapor has to condense, meaning it has to come into contact with cold air.
The RH alone does not matter, and by the way, at the RH of 100 percent, it does not always mean it is going to rain.
The humidity level becomes uncomfortable for people when there is a high dewpoint and a high RH level.
As we saw in the small table that we drew, a dew point of 30 degrees Fahrenheit and RH of 100 percent is quite comfortable.
However, a dewpoint of 60 degrees Fahrenheit and RH of 100 percent is really bad and uncomfortable.
To reiterate what we have been saying all along, check the dew point. If it is high, the humidity will definitely be high and vice versa.
Final thoughts: What is considered high humidity outside?
Humidity outside is considered high when you have a high dew point. Imagine, it is very possible to feel comfortable even with a high RH level. However, if the dew point is higher than 60 degrees Fahrenheit, any RH level can feel uncomfortable.
If you want to accurately tell how damp a day will be, check the dew point level and not the relative humidity level.
The most comfortable humidity level for people is dewpoint of 60 degrees and RH level of 50 to 70 percent. To achieve these levels, the temperature level is usually at 75 degrees Fahrenheit.
Remember, high humidity can cause sickness.
