Generally, a minimum of 5,000mm is good for both skiing and snowboarding in cold but clear conditions, especially if you enjoy taking regular breaks. 10,000mm is ideal for those who spend long days out on the mountain, in most weather conditions; while 15-20,000mm is best for those in wetter climates or when skiing at low altitude or in Spring when the snow is more likely to be falling as sleet or even rain. In these intense conditions, you will get wet it you have not got the right gear. If it rains long enough and hard enough, even the high spec fabrics will eventually fail.
|Waterproof Rating (mm)||Level of Water Resistance|
|0-5,000mm|| No resistance/Little resistance|
|6,000-10,000mm ||Some resistance|
|20,000mm +||Highest resistance|
CAN OUTWEAR EVER BE 100% FULLY WATERPROOF?
Although some materials/fabrics can be fully waterproof, such as rubber and wax, outwear for active sports will usually be offered in varying degrees of water-resistant, I call it (shades of grey) as with enough water, wear, and pressure, all clothing will eventually leak whatever the standard, its just the lesser standards will leak leak sooner.
It is important active outerwear retains an element of breathability, otherwise, you’ll keep the water out but soon be wet from your own perspiration. As a result, most outwear balances protection with breathability.
Conclusion: There has never been a better time to buy high quality ski-wear for the lowest cost but customers have to be aware of the various types of garments and fabrics in use and use them accordingly. So in real terms, what does it all mean. Well If you have a 10,000mm water resistant jacket and its raining all day, will it leak? Quite possibly, Its impossible to tell, but what I can tell you is that if the 10,000mm of saturation is reached while you are wearing it, then yes it will. If it doesn't it wont. This does not mean that the garment is not water resistant or not fit for purpose, it means it was subject to conditions beyond its water resistance limit. This is why you sometimes see officials and stewards wearing plastic ponchos at sporting events, its one of the only methods of trying to guarantee to stay dry. You will sweat bucket loads though!
This is why there are so many levels of water resistance. Its about weighing up the pros and cons for your particular set of requirements. If you are a ski instructor and you have to stay on the slopes for 8 hours every day, every week for months, whatever the weather. Then you need the highest spec fabric, taped seams which costs a lot of money. Most holiday skiers do not need that level of protection and therefore do not need to spend £300+ on a jacket of such high quality. If the weather is terrible you take refuge. You have to decide what works for you. You pay your money and make your choice. My wife is a fair weather skier, doesnt like to ski much in the snow or rain, so for her clothing based on a 5,000mm fabric will be more than adequate for her. My 28 year old son will ski all day, every day and in all weathers. he can use the same lower spec gear but if the weather turned wet, he will run into trouble. He can take that risk and get away with it, as most Alpine days are dry, but if it turned bad for days, he is screwed. Choose the correct level of gear to satisfy your requirements.
So if you are using a garment (jacket or trousers) that has a low water resistant threshold in adverse wet conditions, it will leak sooner rather than later and that's a fact
I hope this helps explain water resistance and water-proofing in skiwear.