The Pacific Northwest rain is relentless—drumming on windows, soaking sidewalks, and turning every trip outside into an adventure in staying dry. And if you've ever reached into your bag only to find your gear damp, you know just how important finding the right fabric for the weather can be.

Some materials barely notice the rain, while others, given enough time, might start to let moisture creep in. So, which fabrics are best suited for a stormy forecast? Let’s dive in.

Waterproof vs. Water-Resistant: What’s the Difference?

Before we talk specific fabrics, let’s break down the basics.

• Water-resistant fabrics can handle light to moderate rain, but if exposed for long enough, water will eventually seep in—often through seams or zippers. Think of them as your trusty rain jacket: great for drizzly days like those here in Seattle, but maybe not the best for a downpour without extra protection.

• Waterproof fabrics are built to keep water out entirely. They have a protective barrier—often a laminate or specialized coating—that prevents moisture from getting through, even in heavy rain. The key factor here isn’t just the fabric itself, but also the construction: fully seam-sealed designs are the best at keeping things 100% dry.

Are TOM BIHN Bags Waterproof?

Short answer: Our fabrics are, but our bags are not fully waterproof.

All TOM BIHN bags are made with “waterproof” fabrics—coated with urethane inside and treated with a water-repellent finish on the outside. Plus, we use YKK water-repellent zippers or cover zippers with fabric flaps to keep rain out. However, because our bags are sewn together, seams can allow some water in if exposed to extreme conditions and some fabric.

We’ve also transitioned nearly all materials to C0 Durable Water Repellent (DWR), a PFC-free finish that repels water while being environmentally friendly.

The Best Fabrics for Rainy Weather

420D Spectron

Our latest and most waterproof fabric, 420D Spectron, is built for rainy climates and those prone to everyday coffee spills (Hey, we’re not judging, it happens more than you think!).

• Water Protection: Excellent

• Best For: Heavy rain, all-weather protection

X-Pac RX30

This laminate fabric is composed of multiple layers. Each layer brings unique properties to enhance performance, making it one of the most water-resistant materials in our lineup.

• Water Protection: Excellent

• Best For: Torrential downpours, high-performance durability

630D & 1050D HT Ballistic Nylon

A versatile favorite across most of our bags, this ballistic nylon balances durability and water resistance.

• Water Protection: High (with an extra-heavy urethane coating)

• Best For: Steady rain, everyday use

200D Halcyon & 210D Cerylon

These lightweight fabrics are commonly used as interior linings but also appear on small accessories. We recommend Halcyon or Cerylon for more temperate days, while using your X-Pac or Spectron for when the forecast is looking wet.

• Water Protection: Moderate (best for light rain, not heavy exposure)

• Best For: Sunny days, minimal moisture exposure

Curious about all the details? Head to our Materials Glossary to learn more about all our available fabrics.

How to Keep Your Bag Dry in Any Weather

Even the best materials have limits. Here’s how to keep your gear safe no matter the forecast:

• Use Packing Cubes or Stuff Sacks: A secondary layer of protection inside your bag can help keep moisture-sensitive items dry.

• Apply a DWR Refresh Spray: Over time, the water-repellent coating on some fabrics can wear down—reapplying it can help maintain water resistance. For the best performance, you can renew your bag’s water-repellent properties using Nikwax or similar treatments.

• Take Advantage of Drainage & Ventilation: If your bag does get wet, empty it out and let it air dry completely to prevent trapped moisture.

Final Verdict: What’s the Best Waterproof Bag Fabric?

All of our fabrics offer a degree of weather protection, however, some truly take the crown when it comes to waterproofing.

If you’re looking for maximum rain protection, choose:

• 420D Spectron or X-Pac RX30 → Best for heavy rain & wet climates
• 630D or 1050D HT Ballistic Nylon → Great for steady rain, not all-day exposure
• 200D Halcyon or 210D Cerylon → Ideal for light rain or interior linings

Stay Dry, No Matter the Forecast

The rain isn’t stopping anytime soon, but with the right water-resistant bag, you won’t have to worry about wet gear.

How do you gear up for and spend your rainy days? Share your stories in the comments below!