Temperature and Humidity for Sports Memorabilia: How to Protect Your Collection

When collectors think about protecting autographed sports memorabilia, sunlight is usually the first thing that comes to mind. But temperature and humidity can also have a major impact on the long-term condition of your collection. See our full guide on caring for sports memorabilia for everything else you should know.

Signed jerseys, baseballs, footballs, basketballs, cards, photos, helmets, and other collectibles are made from different materials. Those materials can react differently to heat, cold, moisture, and changes in the surrounding environment.

The good news is that you don't need a museum-quality storage facility to properly care for most sports memorabilia.

For the average collector, the basic rule is simple:

Keep your sports memorabilia in a comfortable, relatively cool and dry room where the temperature and humidity remain reasonably consistent throughout the year.

Why Temperature Matters for Sports Memorabilia

High temperatures can speed up chemical reactions that contribute to the deterioration of materials. The Smithsonian Institution Archives notes that heat can increase chemical reactions that break down collection materials.

That matters because sports memorabilia can contain all kinds of materials, including:

• Ink
• Leather
• Paper
• Cardboard
• Photographic paper
• Fabric
• Adhesives
• Paint
• Plastics
• Rubber

An autographed football, for example, isn't simply an autograph. You're trying to preserve the signature as well as the football itself.

The same is true with a signed jersey or photograph.

What Temperature Should Sports Memorabilia Be Stored At?

For most collectors, normal room temperature is a practical target.

You don't necessarily need to obsess over maintaining one exact number. In fact, different materials can have different ideal preservation requirements.

What you want to avoid are extreme conditions and major fluctuations.

As a point of reference, the Smithsonian Museum Support Center maintains collection areas around 70°F, plus or minus 4°F, and approximately 45% relative humidity, plus or minus 8%. That doesn't mean your memorabilia room has to exactly match those museum specifications, but it gives collectors a useful idea of what a controlled preservation environment can look like.

A normal climate-controlled room in your home is generally a much better choice than somewhere that becomes extremely hot in July and freezing cold in January.

Why Humidity Matters

Humidity describes the amount of moisture in the air, and too much moisture can create problems for collectibles.

High relative humidity can encourage mold growth and pest activity, while excessively dry conditions can cause some materials to become brittle.

Photographs provide a good example. According to the Library of Congress, high relative humidity can cause the gelatin binder in photographs to become soft and sticky, while low humidity can contribute to shrinking, cracking, and curling. High temperature can further accelerate deterioration.

This is one reason a damp storage room isn't an ideal place for autographed memorabilia.

Consistency Is Extremely Important

One of the biggest lessons collectors should take away from conservation science is that it's not simply about avoiding extreme heat or extreme humidity.

Repeated environmental fluctuations can also create problems.

When temperature and humidity repeatedly rise and fall, materials can respond by absorbing and releasing moisture. Depending on the material, that can result in physical and chemical changes over time. Smithsonian conservation literature specifically identifies rapidly fluctuating temperature and relative humidity as a factor that can compound deterioration.

Think about an upstairs room that gets very hot during summer afternoons but cools significantly overnight.

Or consider a garage that is freezing during winter and extremely hot and humid during summer.

Those are not environments we would choose for a valuable autograph collection.

Is a Basement Good for Storing Sports Memorabilia?

Sometimes—but not automatically.

A finished, climate-controlled basement can potentially provide a very consistent environment throughout the year. That can make it a good location for a collection.

However, don't assume every basement is safe simply because it stays cool.

Unfinished basements can experience humidity, water leaks, flooding, pests, and environmental fluctuations. The Smithsonian specifically cautions that basements and attics can sometimes be among the worst storage locations for personal collections because of these risks.

Before storing memorabilia in a basement, ask:

Is the space climate controlled?

Does it remain dry?

Has the basement ever flooded?

Is there a sump pump, water heater, plumbing, or other potential source of water nearby?

Does the humidity increase significantly during summer?

If the basement is cool, dry, clean, and consistently climate controlled, it can be a good option.

A damp basement is a completely different story.

Avoid Attics and Garages

Attics and garages are generally poor choices for valuable sports memorabilia.

These areas commonly experience much greater temperature swings than the living areas of a home.

A garage might be comfortable during spring but extremely hot during summer. An attic can become even hotter.

You wouldn't want your favorite autographed jersey, rookie card collection, or signed baseballs sitting in those conditions year after year.

A closet or interior room in the climate-controlled portion of your house will usually be a much safer choice.

Temperature and Humidity for Autographed Jerseys

Jerseys should be stored in a stable, climate-controlled environment.

Excessive moisture is something you particularly want to avoid with fabric.

If you're storing jerseys rather than displaying them, don't seal them into a damp environment. Make sure the storage location itself is clean and dry.

If your jersey is professionally framed, you should still consider the environment where the frame will hang.

A professionally framed jersey doesn't suddenly become immune to temperature, humidity, or light.

Temperature and Humidity for Autographed Baseballs

Baseballs contain leather, thread, ink, and other materials that can be affected by their environment.

Keep signed baseballs in a comfortable, dry room and avoid placing them in areas with significant environmental fluctuations.

An individual baseball display case can provide physical protection, but the room containing the case still matters.

Also remember our previous rule:

Keep autographed baseballs out of direct sunlight.

Temperature and Humidity for Sports Cards and Autographed Photos

Cards and photographs deserve particular attention because paper and photographic materials can be sensitive to environmental conditions.

The Library of Congress recommends storing paper materials in a cool, relatively dry, clean, and stable environment and specifically advises avoiding locations with environmental extremes or a high risk of leaks.

Cards should also be kept in appropriate protective holders.

For higher-end sports cards, especially graded cards, a safe or secure storage cabinet inside a climate-controlled area can provide additional physical protection.

Should You Use a Dehumidifier?

If the room where you store your collection is consistently humid, a dehumidifier may be useful.

Don't guess, though.

An inexpensive digital thermometer and hygrometer can tell you both the temperature and relative humidity of your memorabilia room.

This can be particularly helpful in a basement.

Check it throughout different seasons. Your basement may be perfect during January and much more humid during July.

Knowing what's actually happening in the room is better than assuming.

What Relative Humidity Is Best for Sports Memorabilia?

There isn't one perfect humidity number for every piece of sports memorabilia because collections contain many different materials.

As a practical reference, Smithsonian collection facilities have used approximately 45% relative humidity with an allowable range around that target, while Smithsonian guidance for home collections emphasizes cool, dry conditions and notes that excessive humidity increases the risk of mold and accelerated aging.

For a mixed sports memorabilia collection, the larger goal should be a moderate, stable environment rather than constantly chasing one exact percentage.

If your room is consistently extremely humid or dry, that's when you should investigate ways to improve the environment.

Don't Store Memorabilia Near Water

Humidity isn't the only moisture concern.

Think about where you're actually placing the collection.

Avoid storing valuable memorabilia directly underneath:

• Water pipes
• Bathrooms
• Sinks
• Water heaters
• HVAC equipment
• Basement plumbing

Also, don't put valuable memorabilia directly on a basement floor.

A burst pipe or minor flood can cause more damage in a few minutes than years of ordinary storage.

Shelving can provide an additional layer of protection.

A Simple Rule for Collectors

You don't have to make this complicated.

When deciding where to store your sports memorabilia, ask yourself:

Would I be comfortable spending the entire year in this room?

If it's unbearably hot, freezing cold, damp, or constantly changing, your memorabilia probably shouldn't be stored there either.

For most collectors, a clean, dry, climate-controlled interior room with reasonably consistent temperature and humidity is an excellent starting point.

Combine that with proper storage materials and protection from sunlight, and you've addressed several of the biggest environmental threats to your collection.

Frequently Asked Questions About Temperature and Humidity

What temperature should sports memorabilia be stored at?

Normal room temperature in a climate-controlled space is a practical target for most home collections. More important than hitting one exact temperature is avoiding excessive heat, cold, and major fluctuations.

What humidity is best for sports memorabilia?

Different materials have different requirements, but moderate and relatively stable humidity is preferable. As a reference point, the Smithsonian Museum Support Center targets approximately 45% RH, plus or minus 8%.

Can humidity damage autographs?

Excessive humidity can contribute to deterioration of the item and materials surrounding an autograph, including paper, photographs, textiles, adhesives, and other components. High humidity can also encourage mold growth.

Is a basement safe for sports memorabilia?

A finished, dry, climate-controlled basement can work well. A damp or flood-prone basement should be avoided.

Can I store autographs in my attic?

We generally would not recommend it. Attics can experience significant seasonal and daily temperature fluctuations.

Should sports memorabilia be stored in a garage?

Generally, no. Garages commonly experience heat, cold, humidity, and temperature fluctuations that aren't ideal for long-term preservation.

Do I need a humidity monitor?

It's inexpensive and can be useful, especially for large or valuable collections. A digital thermometer/hygrometer lets you see how conditions change throughout the year.

Protect Your Collection for the Long Term

Temperature and humidity aren't necessarily exciting parts of collecting, but they're important.

You've spent time and money building your collection. Whether it's a signed baseball from your favorite player, a framed jersey, or an entire room filled with autographed memorabilia, you want those items to remain in excellent condition.

Remember the basics:

Keep it cool. Keep it dry. Keep it stable. Keep it away from direct sunlight.

Those simple habits can go a long way toward protecting your sports memorabilia.

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Continue Reading: Caring for Sports Memorabilia

Continue with the other articles in our Caring for Sports Memorabilia series:

• Proper Storage for Sports Memorabilia
• UV Protection for Sports Memorabilia
• How to Display & Frame Sports Memorabilia
• How to Clean & Handle Sports Memorabilia
• How to Ship Sports Memorabilia Safely
• Long-Term Sports Memorabilia Preservation
• Sports Memorabilia Display Ideas

Explore the Complete Caring for Sports Memorabilia Guide