What is the humidity and rain relationship? This is a very good question.
Of course, it is always more humid during the rainy season. So yes, there is a relationship. After all, it does seem to mostly rain when the humidity is high outside.
Humidity is moisture or water vapor in the air. For it to rain, the temperature has to drop significantly so that the vapor can condense and eventually fall as rain.
You can also refer to our other article on temperature humidity chart. When the temperature is high and the humidity is high, the air is very uncomfortable. This is akin to something that you are likely to experience in a city like Bangkok, Thailand or in Florida.
What is the minimum humidity for rain?
Some people ask: Can it rain at 60% humidity? And the answer is yes, it can. In fact, it can even rain when the humidity is much lower than that. However, it depends where the humidity is being measured.
Humidity at ground level is not a determinant whether it will rain or not!
So, to the question of: what is the minimum humidity for rain, the answer is 99 percent or 100 percent humidity AT CLOUD LEVEL. Even if the humidity at ground level is 30%, it will still rain if it is 100% at cloud level.
The minimum humidity for rain at cloud level is 100 percent.
While the humidity near the ground will be lower, when it starts raining, it will rise. Thus, do not be surprised to find that you do not need to run your Honeywell humidifier after it has been raining for some time.
Is it more humid before or after rain?
The humidity is more likely to rise during and after raining. So yes, there will be a higher percentage after it rains.
Most people report an increase in humid air after raining. This is normal and it should not cause alarm at all. When the rain stops, it evaporates into the air, thus increasing the humidity level of the surrounding.
In fact, if it is warm outside, the rain will evaporate faster and so the surrounding air will feel more humid.
However, this rise in humid air should only be for some moments. Thus, you should keep an eye on the hygrometer to make sure that the humid session does not extend too much.
If hours later after the rainfall stopped there is still high humidity, you might want to check for a leak in the basement.
If you let indoor humidity run havoc indoors, you will start to see mold symptoms.
Does rain increase indoor humidity?
Rain increases indoor humidity almost immediately after it stops. As we have already explained before, after the rain stops, there is evaporation. This evaporation causes an increase in humidity.
When it is raining immediately, the indoor humidity is not going to increase right there and then. In fact, this is why people say that when the air was too humid, all that it took was a burst of a rainstorm to get rid of the humid air.
Overall, there will be increased humidity immediately after the rain, when it is evaporating. However, a few hours after the rain stops, the humidity should drop, well, unless it is during summer.
The duration that high humidity stays in the air is also determined by how long it rained. If the rain was extended, there will be an extended session of humid air because the evaporation will be more extended.
So, if you have been asking, does rain affect indoor humidity? Yes it does. However, the duration of the humid session should be related to the duration that the rain stayed.
How to predict rain using humidity
Now that we know that there is a relationship between rain and humidity, we are going to find out whether you can use the humid state of the air to foretell rain.
If the air is really humid, it is more likely to rain. The reason for that is that if there is more water vapor in the air, it is going to condense at low temperature. With more condensation, the clouds become too heavy and precipitation follows soon after.
So many things can affect the coming of rain when the air is humid. For instance, winds can determine whether it rains or not. Thus, it must not always rain just because the air is humid.
All we are saying is that humid places are more likely to receive rainfall than places with dry air.
Humidity and Rain Relationship Final Thoughts
Humidity must reach 100 percent to rain because at 100 percent humid level, the clouds cannot hold any more water and so, it just rains!
Also, knowing how rainfall affects the indoor humidity is very important. You can prepare in advance with humidifiers and dehumidifiers. Better yet, make sure they come with sensors so that they can turn on and off automatically when the need arises.