Does Rain Cause Humidity? [Indoors & Out]

Humidity levels change depending on conditions inside and outside a home. As a homeowner, you might already know that seasons affect humidity, like summer or winter. But does the same principle apply to different weather conditions? If you're wondering if the humidity rises when it rains, we've looked it up and have the answers for you in this post!

Yes, humidity levels increase during and after it rains primarily because of evaporation. When rain evaporates, the moisture it carries transfers to the air. And so, the more it rains, the higher humidity will become. The same goes for when the surrounding temperature gets warmer as it rains and when it stops.

We can say rain will likely make the air more humid, resulting in damage to properties. Fortunately, there are ways to lower humidity inside and outside a home. Keep reading to know how humidity affects your surroundings and how to deal with it.

Raindrops on a window pane during rainy weather, Does Rain Cause Humidity? [Indoors & Out]

Will Humidity Increase When It Rains?

Yes, rain can cause an increase in humidity due to evaporation. Rain saturates the surrounding air with water vapor in this cycle, resulting in rising moisture levels.

As the rain pours, the air will continue to draw water, causing it to take in more moisture. But in some instances, the rain will reduce relative humidity by cooling the air through increasing moisture content. However, it also varies on other factors, such as outside temperature, rainfall amount, and space size.

Condensation on window glass caused by high humidity in winter

Keep in mind that humidity changes influence inside and outside conditions differently. Here's a brief on how it works:

How Rain Affects Indoor Humidity

Homes usually have an HVAC system to control air quality, so it is less likely that outside air will change inside conditions. If it does, it suggests leaks causing outdoor air to enter.

The humidity inside is initially different from the humidity outside. Humidity is bound to increase outdoors when it rains. If a house has poor ventilation and gaps in the foundation, extra moisture can pass through and spread, increasing humidity significantly.

How Rain Affects Outdoor Humidity

Outside environments have direct exposure to rain, meaning the humidity mainly changes depending on the temperature. Rain evaporates and increases moisture when it's warm, making it more humid. But it cools the air when the temperature is already cold, which reduces humidity instead.

Does Humidity Affect Your Home?

rain drops on glass texture abstraction people behind the glass

Humidity is a huge component in determining air quality and comfort within your home. If it's at a level too high or low than recommended, it can lead to undesirable effects. These are as follows:

Bacteria Growth

Mold and mildew thrive in warm, damp locations and spread across different areas of a home under the right conditions. The presence of mold leads to several other complications, including unpleasant smells, damage to surfaces, and infection or allergic reactions.

Musty Smells

A humid room may give off a musty odor due to stuffy temperature conditions. It could also come from the mold or exposed dirt coming from leakages or gaps around the room.

Higher Cooling And Heating Costs

If your home isn't at the appropriate temperature, your HVAC system will need to exert extra effort to heat or cool a room until it reaches the optimal climate. And so, it consumes more power, which adds up to higher energy costs.

Health Issues

Poor air quality can also affect human health by triggering allergies or causing air infections. Sometimes, it may lead to dehydration due to excessive sweating and fatigue because of sleeping troubles.

Property Damage

Humidity can also harm your property, ranging from cosmetic to structural damage, varying on room condition. In most cases, it costs a lot to make the necessary repairs.

How To Measure Relative Humidity

hygrometer Gauge

You can identify the adjustments you need to keep the air comfortable by measuring humidity levels. Listed below are a couple of methods you can try to determine relative humidity:

Using A Hygrometer

A hygrometer is a specific tool designed for measuring humidity in connection to relative humidity. It works by measuring the amount of moisture in the air.

The device can be bought separately or installed in modern dehumidifiers. If you have it in your dehumidifier, your unit automatically adjusts its settings to control humidity.

Click here to see the ThermoPro Digital Hygrometer on Amazon.

Wet And Dry Bulb Test

The wet and dry bulb test uses wet-bulb and dry-bulb thermometers and their measured temperatures. Here, the dry-bulb thermometer produces standard temperature while the wet-bulb thermometer measures the temperature of water evaporating into the bulb.

To try the test, start by running a fan in the room where the thermometers will go later. Take one of your thermometers and attach a damp cotton ball on the bulb, preferably using room temperature water.

Bring the thermometers to the room with the fan and place them where the air blows on them. Leave them for about 5 minutes before comparing the temperature readings.

Subtract the dry-bulb temperature to the wet-bulb temperature, then refer to this chart to determine the relative humidity using the calculated answer and the dry-bulb temperature.

Ice Cube Trick

If you want to know if the room is too humid or too dry, you can try the ice cube test. You only need to take a glass of water with about 4 to 5 ice cubes, then leave it in the room you want to check for about 5 minutes.

If condensation forms around the glass, the room has relatively high humidity. If there is no condensation, then the humidity levels are low.

What To Do To Balance Humidity?

A Knob Labeled Balance Set in the Middle as Perfect

Generally, the recommended relative humidity level for comfortable conditions is between 30% to 50% on typical days and around 30% to 40% during warmer seasons in a colder climate.

Read more about the required humidity levels in a home in this post: What Should The Humidity In My House Be?

Keeping it within this range may require adjustments in your environment, especially during extreme temperatures. Below are a few tools and strategies to help you control humidity inside and outside your home:

Tips For Dealing With Humidity Indoors

Indoor air is easier to regulate because it takes up only limited space and stays within a closed area. Common ways to adjust humidity involve using different systems and devices, like the following:


Experts suggest using a dehumidifier in a house, especially in locations prone to moisture buildups, like basements or attics. The unit reduces moisture by extracting water from the air before releasing it into the room.

When using a dehumidifier, note that most models cannot operate in temperatures under 60 degrees Fahrenheit since it could damage the unit. So, it's best to put it away during the winter.

Get the Waykar 2000 Sq. Ft Dehumidifier on Amazon.

Air Conditioning

Air conditioners do more than keep the air cool. It also reduces humidity by eliminating warmth and moisture from the air, contributing to temperature regulation throughout the home.

Check out the Black + Decker Portable Air Conditioner on Amazon.


Weatherstripping creates a tight seal around doors and windows to keep air from escaping or seeping into a room. Closing off these small gaps makes a huge difference to the efficiency of your indoor systems to control and maintain temperature.

Click here to get the Magzo Weatherstrip Adhesive on Amazon.


Like weatherstripping, caulking is a sealing method used on foundation surfaces or materials that come in contact with moisture. These can be walls, sinks, tubs, and more. You can also apply this on leaks around windows and the like.

Check out the Gorilla White Silicone Caulk on Amazon.


Man insulating the attic with rock wool

Insulation provides resistance to heat flow to and from different surfaces and areas, allowing temperatures to become more stable. It creates a barrier that prevents too much warm and cool air from passing through to keep conditions comfortable.

Proper Ventilation

Ventilation gives humid air a route to escape instead of staying trapped indoors. If your home has enough ventilation, it maintains proper airflow, wherein air gets naturally conditioned.

Read this post for a more tips on reducing humidity naturally indoors: How To Naturally Reduce Humidity In A Room

Tips For Dealing With Humidity Outdoors

It's almost impossible to manage and control outdoor humidity with all the factors involved. However, there are a few things you can do to prevent it from negatively affecting your home, such as:

Drainage, Gutters, Downspouts

Clean your drainage, gutters, downspouts, and the like regularly to prevent clogging. At the same time, make sure they slope away from your home. That way, they don't run down your foundation.

Roof And Vent Inspection

Get regular inspection for roof and vents to locate cracks and deterioration that may require urgent replacement or repair.

Sloped Ledges

Consider installing sloped ledges or awnings above your windows and doors to ensure water flows away from these openings.

The Bottom Line

Raindrops on a window pane during rainy weather

When rain evaporates, it causes humidity to rise due to the increase of water vapor in the air. Indoor and outdoor temperatures may change because of these conditions. However, you can regulate humidity levels by using different systems and making structural adjustments.

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