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How does temperature affect a helmet?

helmet temperature heat cold

Extremes of temperature can affect your helmet so it’s important to store it somewhere that is temperate and dry.

A rider posted the above photo of his adventure helmet which he had stored in his shed during summer.

It’s obviously a polycarbonate shell which has melted in the extreme temperatures.

While this is an extreme case, temperature, sweat, humidity and exposure to UV rays can reduce the longevity of your helmet.


Most helmets are tested for extreme temperatures, usually up to over 50 degrees centigrade and down to -7 in Australia and -22 for European-approved helmets which are now legal in Australia.

So your helmet shell isn’t going to melt, crack or fall apart just from temperature extremes. No one would ride in those temperatures, anyhow.

The interior foam is the same as used in refrigerators and some roof insulation, so it should also not be affected.

However, I’ve stored helmets in my office over summer, sitting on my desk in temperatures up to 40 degrees and the bottom has melted to the desk.

helmet temperature heat cold
Black marks where the helmet has melted to the desk

So, while the shell and foam should be ok in extremes of temperature, it does have an effect on the soft lining materials.


The biggest affect on your helmet’s life is your own sweat.

It degrades the interior lining, causes the adhesives to fail and compresses the foam making the fit of the helmet loose and less effective than when it is tight.

If you start to see black flakes on your head when you take your helmet off, it’s probably time to buy a new helmet.

Hair products can also have a detrimental affect on the helmet lining.

You can prevent sweat and hair products from ruining your helmet by wearing a bandana, balaclava or skull cap. 

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You can also reduce the effects of sweat and hair products by regularly washing the lining if it is removable.

If not, spray the inside with special helmet interior cleaner.

Make sure the lining is dried slowly and thoroughly inside, not in direct sunlight.


Like sweat, humidity also has a significant effect on helmet linings, causing mould.

If you live in a humid climate, store the helmet in the bag it came in.

When you bought your helmet, you will have noticed a small bag of silica gel flakes came with the packaging. Don’t throw them out, even though they may say “Throw away” on the pack.Silica gel packets Helmet Heat Deformed How does temperature affect a helmet?

In fact, save those little bags of silica gel flakes that come with a lot of new products. They have a limited life, but can still absorb some moisture. You can also buy the gel packs separately.

They can be useful for storing with your helmet, gloves and other riding gear, especially if you are not using your helmet or gear for a long time, such as over winter.

In which case, make sure there are no mice where you store your gear as they love to chew the soft interior and turn it into bedding!


Helmet shells are tested to withstand temperature extremes, but constant exposure to the UV rays in sunlight will gradually degrade the material.

Visors also tend to get a creamy, frosted look from long exposure to sunlight.

While there is nothing you can do to protect your helmet and visor from sunlight when you are riding, it is important to store your helmet in the shade or in the bag it came in.

Don’t put it by the window where the sun comes in or store it on the back deck of your car.

  1. Don’t bother saving the silica jell packets. Once they are out of a closed environment like a cardboard box they will rapidly absorb the water vapour in the air and be useless within a couple of days.

    1. silica gels absorb moisture, then it turns dry. continuously available. Do not comment without knowing

      1. As a Chemical Engineer, I can attest to Robert’s comment. The silica gels will become useless after just a few days. You should follow your own advice.

  2. 303 Protectant. Protects against UV.
    Been around for 20 years. Used by boat and marine ppl on plastic and vinyl.
    Rated at SPF 40.
    Supercheap are now stocking it, but it’s not cheap. Harrr.

  3. As above, silica gel absorbs moisture out of the air, however you can reactivate it by placing it in an electric oven on low. It will need to be out of the sachet so that you can see the colour change from pink to blue which indicates it’s given up its moisture. Needs to be done in an electric oven, not gas as gas gives off water and CO2 when burnt and the water will be reabsorbed by the crystals.

  4. Temperature effects the EPS density. Helmets are tested hot and cold to ensure they still comply the standard. The colder the stiffer and visa versa.

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