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Parents, beware! The one material you should never dress kids in during a heatwave

Harri Mellor, co-founder of Our Little Wardrobe, gives HELLO! the lowdown

Katie Daly
Lifestyle Writer
June 30, 2025
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For the last couple of weeks, Brits have been battling the heatwave with fans, cold drinks, and plenty of suncream.

But for parents, many will be concerned about the best clothing to dress their little ones in. Balancing the right amount of coverage to protect their skin from UV rays while keeping them from overheating can be a tricky balance.

The key to striking the balance is choosing the right fabric, and there is one that parents need to avoid. Harri Mellor, co-founder of Our Little Wardrobe, gives us all the details…

Which fabrics should parents avoid dressing their kids in?

Whether it's shorts and T-shirts or dresses, Harri says polyester and synthetic fabrics are a no-no. 

girl relaxing in kiddie pool© Getty Images
Harri warns against synthetic fabrics

"These trap heat and moisture, preventing proper airflow," she says. "Children are more prone to overheating, and synthetic materials can increase the risk of heat rash or skin irritation."

She also says there is a fabric that might appear heatwave-proof, but should be avoided – nylon. "Though lightweight, it’s not breathable and holds sweat against the skin," she reveals.

Natural fabrics keep kids cool© Getty Images
Natural fabrics keep kids cool

Fleece or thick knits should also be left in the wardrobe, Harri says, as they insulate the body, which is the opposite of what you want in high temperatures. While not a fabric, it’s worth noting that dark colours absorb more heat from the sun and can raise body temperature.

Which fabrics are heatwave-proof for kids?

Instead, Harri says cotton is perfect for hot summer days. She tells us it is lightweight, breathable, and absorbs moisture, making it ideal for sensitive skin and easy to wash.

"Natural and extremely breathable, [cotton] allows for airflow and dries quickly, making it perfect for hotter climates," she adds, recommending an alternative. Harri also loves bamboo for its soft, hypoallergenic, and moisture-wicking properties, and its ability to offer some natural UV protection.

Portrait of boy & girl holding hands and laughing © Getty Images
Harri likes a linen romper for keeping kids cool

Muslin is also excellent for young children or babies due to its ultra-lightweight, soft, and breathable qualities, while Tencel is eco-friendly, breathable, and helps with moisture regulation.

Portrait cool girls together on blue backdrop in summer© Getty Images
Cotton and linen help kids regulate their temperatures

When it comes to finding the right outfit for your little one in the heat, Harri recommends putting together the following five ensembles:

Loose-fit cotton T-shirt and shorts

  • Breathable and easy to move in; opt for light colours to reflect heat.

Linen romper or playsuit

  • For toddlers and babies, a sleeveless linen one-piece keeps things cool and stylish.

Muslin cotton dress or tunic

  • Ideal for girls, muslin is featherlight and airy. Pair with a cotton sunhat.

Bamboo pyjamas for hot nights

  • Great for sleep comfort, especially if your child runs warm at night.

Wide-brim hat and UV-protective swimwear

  • For outdoor play or beach days, look for UPF-rated swimwear and accessories made of breathable, quick-dry materials, as well as rash vests.

Oversized cotton shirt and shorts

  • Doubles as sun protection; easy to layer over a swimsuit or tank.
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