They key to comfort in any weather condition is waterproof-breathable outerwear. It’s the first step to staying dry so you can focus on having fun outside, no matter the weather conditions. There are many different types of water-resistant fabrics used to make outerwear.

Manufacturers typically describe the waterproof and breathability ratings of fabrics using two numbers, often separated by a backslash. The first number is waterproof, the second is breathability. The origins of these ratings are in a scientific lab, but the bottom line is simple - the higher the rating, the more waterproof, and the more breathable the garment.

Waterproof ratings are determined by lab testing involving protocols to test a fabric’s water permeability under pressure.  Some lab tests involve adding pressure to the process to simulate the effects of wind.  Breathability ratings are also determined by lab testing using diverse methodologies and often impossible to compare because results can vary wildly based on atmospheric conditions, and most testing doesn’t reflect these conditions.  Since manufacturers seldom reveal the actual test used and are typically keen on reporting the highest possible figures to promote sales, it’s best to read these numbers with skepticism, but generally within a given brand or family of fabrics it’s safe to say more mm of waterproofness is best and more grams of breathability is best.