What Temp Should The Attic Fan Be? (Summer Time!)

From the beginning of June to the end of September, it is always a huge task to keep your attic cool at the right temperature as the summer is a season where heat and humidity are the highest.

While your attic has a fan that can be adjusted correctly to make it comfortable for you, the problem is always how to know the right temperature to set the attic fan to.

In this article, we will look at what the normal temperature should be for your attic during summer, at what time and temperature you should turn your attic fan on, and at what humidity your attic fan should be set at during summer.

Here’s The Temp For Attic Fan Should In The Summer:

Due to the variation in the temperature during summer, it is impossible to give an exact temperature value.

Thankfully, most attic fans have a thermostat that allows you to set temperatures for the fan to go on and off automatically.

But if your attic fan doesn’t have a thermostat, it simply means you will have to switch it on and off manually.

So it is often advised to set your attic fan to between 90 and 110 degrees Fahrenheit.

(Some manufacturers also recommend between 100 and 110 degrees Fahrenheit)

The ultimate guide to making your final decision is ensuring that your attic stays less than 10 degrees Fahrenheit below the daily forecast.

So you must try not to raise the fan temperature too high, even while working in the range of 90 and 110 degrees Fahrenheit.

What Is The Normal Temperature For The Attic In Summer?

Generally, your attic temperature should be close to the outdoor temperature. At most, it should be 10 to 20 degrees warmer. Also, your attic should not exceed 130 degrees Fahrenheit on the hottest summer days.

You must keep your attic at a normal temperature so that you don’t damage your belongings.

Excess heat or humidity can damage your prized properties, no matter how protected they are.

So you must ensure that your attic fan is set correctly to keep your attic temperature in the normal range.

Another reason you have to maintain your attic at a normal temperature is so that you can preserve the normal functioning of your air conditioner and central cooling system of your home.

When the heat is too much above normal in your attic, it can get your air conditioner to supply your home with air that might be too cold and this can become overwhelming.

So you must ensure your attic is kept at the normal temperature if you want your air conditioner to supply cool air to your home only the way you need it.

Also, your attic can become an environment for molds to thrive if it gets hotter than normal. It can even degrade some of your insulations, especially those made of cellulose.

At What Temperature Should An Attic Fan Turn On?

Generally, you should set your attic fan to turn on at about 90 degrees Fahrenheit.

But the best way to go about this is to measure the average temperature where you can be comfortable in your attic and set the attic fan to be just around that.

It is also important that you ensure the temperature of your attic fan is higher than the temperature of the surrounding so that the fan’s motor does not burn out.

A good way to go about these processes to arrive at a temperature that works perfectly for you is to install a thermometer that you can see from your attic hatch.

You can then check regularly and take note of the readings over a couple of days or weeks. And once you have identified the best temperature, you can simply try to adjust it with the temperature of your surrounding and the day length.

Over time, you will notice that you have succeeded when the ceiling of the adjacent rooms of the attic becomes cooler and much more comfortable.

When Should I Run My Attic Fan In The Summer?

You should run your attic fan anytime your attic gets hotter than your desired comfort level. A good way to know when it is time to run your attic fan is from any room near your attic.

The attic generates a lot of heat during summer. So if you touch the ceiling that is adjacent to your attic and feel so much heat radiating into the room, then it is probably time to turn your attic fan on.

If your attic does not have a thermostat, simply turn the fan on, let it run the correct amount of time and then turn it off again. You can then wait for a few hours and repeat the process.

(Running it longer than needed will only waste your electricity and increase your bills)

But if your attic fan has a thermostat, you should simply set the “switch on” temperature just around the temperature you will love the attic to remain at.

Since you will not want your fan on all summer long, you must make sure to set the “switch on” temperature to a temperature that is not too hot but hot enough to ensure that your fan is not always on.

You will only create a noisy disturbance for yourself, increase your utility cost and reduce the lifespan of the fan if you don’t set the temperature properly.

You should also note that attic fans work best at night since the air in the surrounding is very cool and be exchanged with the warm air in your attic.

What Humidity Should The Attic Fan Be Set At In Summer?

The best humidity level to set your attic fan on is between 50% and 70%.

So if your attic fan has a humidistat, this means that the attic fan will automatically switch on once the relative humidity in the attic exceeds the set value.

It is especially important to pay attention to this because unlike heat, humidity is not directly related to temperature. Instead, it is related to atmospheric moisture and moisture from cooking, showering, breathing and other activities within the house.

So you don’t need the surrounding air to be very hot before humidity levels rise in your attic.

And you must watch humidity levels closely so you do not allow molds to build up in your attic.


When setting the temperature of your attic fan, always remember to ensure that your attic does not go more than 10 degrees hotter than the surrounding.

But if you find out that your attic is still getting hotter than it should normally be, then you might need to check the insulation of your house.