When temperatures rise, most people think about holidays, barbecues, and long days outside, not what’s happening inside their storage unit.
But heat can cause serious damage to your belongings if you’re not prepared. From warped vinyl to damaged electronics, summer conditions can take a toll on items stored without the right precautions.
The UK is getting hotter, and according to the Met Office, 2025 was the UK’s warmest and sunniest year on record, with consistently above-average temperatures across spring and summer. That means storage unit temperature is becoming a bigger risk year after year.
Our summer storage tips will help you understand what’s at risk, what to check before a heatwave hits, and how to protect your most valuable items.
6 Items at Risk From Summer Heat in Your Storage Unit
Not everything handles heat well. Some everyday items can deteriorate surprisingly quickly in high temperatures, especially in non-climate-controlled storage units.
1. Electronics
Heat and electronics are a bad combination. High temperatures can:
- Cause batteries to swell or leak
- Damage internal components
- Lead to cracked screens or warped casings
Tip: Store electronics in their original boxes where possible and avoid placing them near walls or ceilings where heat builds up.
2. Vinyl Records and CDs
Vinyl records are sensitive to heat and can warp permanently if exposed to high temperatures. CDs and DVDs can also degrade or become unreadable.
Tip: Store them upright in protective sleeves and keep them in the coolest part of your unit.
3. Candles and Wax Items
Candles, cosmetics, and anything wax-based can melt quickly in hot conditions, leading to messy and irreversible damage.
Tip: Avoid storing these items during summer altogether if possible.
4. Photographs and Paper Items
Heat combined with humidity can cause photographs to:
- Fade
- Stick together
- Become brittle
Tip: Use airtight plastic containers to reduce heat and moisture exposure.
5. Leather Furniture
Leather is particularly vulnerable in hot conditions. It can:
- Dry out
- Crack
- Lose its natural oils
Tip: Cover with breathable fabric and avoid direct heat exposure.
6. Plastics and Rubber
Some plastics can warp, while rubber can become brittle over time.
Tip: Keep these items out of direct heat, avoid stacking heavy items on top, and store them in shaded areas of your unit.
If you’re unsure what not to store in summer, take a look at our guide on things you should never put in a non-climate-controlled unit here.
Quick Summer Check – Do This Before the Heatwave
A quick visit to your storage unit before temperatures peak can help prevent long-term damage.
- Visit your unit in person
- Check for condensation or damp
- Move heat-sensitive items away from walls and ceilings
- Review your storage setup
- Consider climate-controlled storage
- Update your inventory
Heatwaves are becoming more common in the UK, with scientists warning that extreme heat is now occurring more frequently and lasting longer than in previous decades.
If you’re storing valuable items, it’s worth checking whether your current setup is still suitable, especially when considering climate-controlled storage.
Storage Insurance
Cover includes:
- Theft, Fire, Flood, Pests & More
- Instant Certificate via Email
- No Hidden Fees & No Excess
- 90% of Customers Save With Us
Simple Steps to Protect Your Most Valuable Items
You don’t need to overhaul your entire storage unit to reduce the risk of heat damage. A few simple changes can go a long way.
- Use Plastic Containers Instead of Cardboard: Cardboard can absorb moisture and weaken in heat. Plastic containers offer better protection from both heat and humidity.
- Keep Items Off the Floor: Use pallets or shelving to raise items slightly. This helps protect against both heat build-up and potential damp.
- Use Silica Gel or Moisture Absorbers: These help control humidity levels inside containers and reduce the risk of mould or damage.
- Wrap Electronics Properly: Anti-static bags or protective covers can help prevent internal damage caused by heat and static.
- Allow Airflow: Don’t pack items too tightly. Good air circulation helps prevent heat from building up in one area.
- Avoid Overfilling Your Unit: An overpacked unit traps heat more easily, increasing the risk of damage.
Think Carefully About What You Store: Some items are not suitable for storage in warmer months. Read our guide on personal valuables you should never store in self-storage.
Don’t Forget Seasonal Risks Go Both Ways
While summer heat can cause damage, winter brings its own risks too, from damp to freezing temperatures.
If you use storage all year-round, it’s worth understanding how conditions change across seasons. Our article on risks when using self-storage in the winter explains further.
Final Summer Storage Tips to Prevent Heat Damage
Even with the best summer storage tips in place, unexpected issues can still happen. That’s why it’s important to make sure your belongings are properly protected, especially during periods of extreme heat when storage unit temperatures can rise quickly.
Taking simple steps to prevent heat damage in your storage unit, like using the right materials, improving airflow, and considering climate-controlled storage, can help you avoid expensive problems and keep your items in good condition.
For more ways to protect your belongings and explore your options, take a look at our storage insurance cover.
