Our customers often ask us: “Will my RainSisters coat really keep me dry?” The short answer is, yes – our coats are designed with a high-quality waterproof fabric rated at 10’000 mm, making them more than capable of withstanding everyday rain. But what does 10’000 mm waterproof actually mean? And how does it compare to other types of clothing? Let’s break it down! 


What Does “Waterproof” Actually Mean? 

In the world of outerwear, waterproofness refers to how well a fabric can prevent water from passing through it. To measure this, fabrics go through something called the Hydrostatic Head (HH) test. 

The way it works is, a column of water is placed on the fabric, and the measurement in millimetres (mm) shows how tall the water column can get before the water starts seeping through. A fabric with a 10’000 mm rating can hold back a 10-meter column of water before the water starts to seep through it. The higher the number, the more resistant the fabric is to water pressure. 

Customer Candela in Galway, Ireland, wearing RainSisters 'Queen of Hearts' coat


Waterproof Ratings Explained 

According to the industry standards and practices, anything that has a rating of at least 5000 mm and above can be called “waterproof”. To better help you understand what different ratings mean in practice, here are a few examples of different waterproofness ratings: 

  • 0 – 5000 mm: light protection – suitable for very light rain or as a fashion layer, but not designed for real weather.
  • 5000 – 10’000 mm: good protection – works for everyday rain and light snow, perfect for commuting or casual outdoor wear. 
  • 10’000 – 20’000 mm: high protection – often found in quality ski jackets or hiking gear, designed for heavier and more prolonged exposure to wet weather. 
  • 20’000+ mm: extreme protection – technical mountaineering jackets designed for severe weather and hours of exposure.  

Model Alexandrina in Paris, France, wearing RainSisters 'Violet Bloom' coat

 

With a 10’000 mm waterproof rating, RainSisters coats fall into the same category as good ski jackets or high-quality kids’ outerwear. That means they are more than capable of keeping you dry through everyday showers, commutes, and even heavier bursts of rain. 


Light, Moderate, and Heavy Rain: What’s the Difference? 

Not all rain is created equal, not to even mention, that every person might have a different concept for what could be considered as light or moderate rain. But here’s how meteorologists generally define rainfall intensity:

  • Light rain: 2.5 mm or less per hour (a gentle drizzle)
  • Moderate rain: 2.5 – 7.5 mm per hour (steady rain that may require an umbrella or a coat) 
  • Heavy rain: 7.5 – 50 mm per hour (downpours, soaking showers) 
  • Very heavy/extreme rain: 50+ mm per hour (tropical-style storms) 

Model Katya in Portugal wearing RainSisters 'Graceful Gray'

 

By definition, as well as our own and our customer experience, RainSisters coats are fully capable of handling light and moderate rain, and even heavy rain for shorter periods, like, commutes. The soft shell and light shell fabric used for our coats protects you from soaking through, while the elegant tailoring ensures you still look refined and feminine. In addition, there’s also membrane material, that won’t let the water soak through. In other words, your RainSisters coat can get wet, but it won’t soak through. 


The Role of Seams and Stitching 

When it comes to outerwear, it’s not only fabric that matters – construction plays a big role in waterproofing. Many technical outdoor jackets (like mountaineering gear) use taped or sealed seams, which block water from seeping through the tiny holes created during stitching. 

RainSisters coats, however, are not seam-sealed, because our focus is on combining elegance with functionality, rather than technical sportswear. This means:

  • The fabric itself is fully waterproof (10’000 mm),
  • During long periods of very heavy rain, some water may eventually seep in through the seams. 

Customer Natalia in Estonia, wearing RainSisters 'Raspberry Sorbet'

 

For the majority of our customers, this isn’t a concern, because our coats are designed for everyday urban wear, commuting and light outdoor activities, not for spending hours in alpine storms.   


Why 10’000 mm Is More Than Enough for Everyday Life 

To put things in perspective:

  • A typical umbrella fabric has a waterproof rating of around 2’000 – 3’000 mm.
  • Many everyday rain jackets sit at 5’000 mm. 
  • High-quality ski jackets usually start at 10’000 mm.

That means, your RainSisters coat has the same level of waterproof protection as a ski outerwear – but in a silhouette that looks more refined and timeless. For everyday wear, our coats are the perfect blend of fashion and function, helping you face unpredictable weather without compromising on style. 

Ready to choose your favourite RainSisters coat? Check out our catalogue here! 

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