Windshirts, sometimes called windbreakers or wind-shells are one of the most versatile pieces of clothing you can use. A simple, unlined windshirt can ounce per ounce provide more warmth than many other clothing items because it helps prevent convection cooling which increases significantly as the wind speed increases. In many cases a windshirt over an appropriate weight base layer is all you need to keep comfortable when active. Windshirts can protect you from many biting insects. Wind shirts slow evaporation a bit (they are not perfectly breathable) which moderates flash-off cooling. Finally, a good wind shirt can keep you comfortable (but not necessarily dry) in a light drizzle when a full rain shell would be too much.  Ideally you want some air permeability to maximize breathability while still providing protection from convection cooling.

My Choice

I use a Black Diamond Alpine Start which is a ultra-light softshell which is fairly air permeable (listed as CFM 40, but feels more like 60) which I use when biking and running in the Bay Area winters. It is more durable than most wind shells, the Schoeller NanoSphere treatment lets it shake off light rain (and dry very quickly). I have a 2012 ArcTeryx Squamish windshirt which has an air permeability around 30 CFM. It’s more durable than many of the lighter wind shells, and it’s slight textual feels better against the skin than many other options. Note: my understanding is the current Squamish isn’t as as air permeable. Finally I have a I also have an amazing light, breathable, and pricy shakedry rain shell that I sometimes use instead of a wind shirt when I am minimizing what I carry. I have found shakedry fabric is approaching the breathability of a windshirt but is not very air permeable.

Classic Windshirts

Classic windshirts are ultra-light, ultra-breathable unlined nylon or polyester jackets which block the wind while being highly breathable. I am particularly fond of windshirts with hoods and full zippers such as the MH Kor Preshell, REI Flash Jacket, ArcTeryx Squamish, and Montbell Tachyon. I have heard good things about the EE Copperfield but not personal experience. I used to like the Patagonia Houdini, but in recent years it seems like the cut isn’t great, they aren’t breathable enough, the the fabric is kind of noisy. It seems many of the manufacturers change the materials in these wind shirts almost every year… I have a hard time following them.

Stretch woven softshells can be a good alternative to wind shirts. They tend to be more air permeable and more durable than a classic wind shirt. This makes them great for high energy activities and/or when engaged in activities that are hard on clothing like climbing.

Some people use rain gear for wind protection. In warmer weather, most rain gear is not sufficiently breathable and tends to retain too much heat. They block the wind too well, the wearer will often overheat and get wet from sweat. A counter point is that if you either manage you activity level and/or are in cool weather rain shells can work.

There was a nice discussion about breathability, CFM and wind shirts windproofness, breathability, and air permeability , how breathable a wind shirt is, visual paradigm for wind shirts, comparison of montbell tachyon and patagonia houdini air on a BPL forum. When backpacking a CFM between 30-40 is considered optimal. There is a thread on reddit about finding 40CFM windshirts. Note: I find that a traditional supplex hiking shirt feels like it has a bit less air permeability than a 40cfm shell, and more wind blocking that the Dooy which is reported to be around 60cfm which I find too much for many use cases. When running or engaged in other high aerobic activities, 70-90 CFM is typically optimal. Most people can’t perceive wind if a material is CFM of <=5. A discussion about older (2012-2014) Squamish wind shirts. There is a nice article about High Exertion Moisture Accumulation in Rain and Wind Shells. There is a thread on BPL about

Low Cost:  The cheapest solution is a cheap nylon windbreaker found at Target, Walmart, Dooy on Amazon (though it’s air permeability CFM 60 is a bit higher than I typically want), the women’s windshirt on ebay, etc.  Discussions on BPL about Fauxdini. Personally, I don’t get the dooy/fauxdini love. They seem to have about the same air permeability as a supplex hiking shirt (e.g. too much when I really want protection from the wind). There are a number of articles with lab test by Stephen Seeber, properties that effect air permability, and a articles which compares field and lab results.

You’ll wear it when the rain comes down,
You’ll wear it when the wind blows ’round.
You’ll wear it when the temps are low,
You’ll wear it when it starts to snow.
You’ll wear it while the flies do swarm,
You’ll wear it when the sun is warm.
So skeeters, wind, rain, snow, or sun,
A wind shirt is for everyone.

Ode to a Wind Shirt from Clothing and Sleep Systems for Mountain Hiking

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