Wind Shirts

Much of this will be subjective…

For me, on multi-day hikes where rain might be a factor, I prefer to carry a lightweight wp/b rain jacket — and let it do double duty as a wind breaker. I never carry both rain and wind shells.

For three-season day hikes where rain is not forecasted, I'll carry my lighter weight wind jacket. Even if the forecast is wrong, I'm not that far away from the trailhead.

A wind jacket is generally lighter and more breathable than a rain jacket. The wind jacket's higher breathability sometimes means that you can keep it on longer while you hike — versus frequent zipping / unzipping, putting it on and taking it off. But there is a limit to this advantage.

Some folks seem to be on a quest for "the most breathable" wind shell out there. But IMO, there should be a balance between breathability vs. wind blocking. When you reach your destination and rest up, a wind shirt that's "too breathable" may be lousy at blocking out the cold winds!

Kevin; it was a new layering concept for me too. Now I always carry my windshirt. Pros are that it blocks a little wind and a little precipitation while being much more breathable than a rain shell. Cons are that it only blocks a little wind and a little precipitation.
Searching the forums for 'windshirt' (one word) generates more than 1000 hits. Its a popular topic of discussion, and this 'wind layer' (including wind pants) is not even in most heavyweight backpackers vocabulary. I had to add the wind layer to the wikipedia article on layering because it was not even mentioned yet.
Mine is a Patagonia Houdini, but any breathable single layer nylon jacket with DWR coating will work.

I was sort of always on and off with windshirts, but here is a great example of its use.

I was taking a longish day hike with some family friends, 9 mile circuit through the White Mountains (Lincoln, Haystack, and Lafayette). The going was quite slow for our whole group of 8, and I was perfectly warm in what may have been 40-50 mile per hour winds at the ridge with only a windshirt and a mid weight tee shirt. When the clouds were out i zipped it up and when we descended to warmer areas I zipped all the way down and was fine. I would disagree that it lets wind through, the trick is to get the trimmest fitting one that you can, so you don't get the billows affect of the wind flapping air away through the openings, which also creates a really annoying noise. The mountain clothing article from a couple years back really gives a glowing review of the windshirt, and even if you don't like the little water resistance it has, it makes up for its reliable trapping of warm air that only a shell would do, but without leaving the moisture in too.

Hope this helps

I can't comment to anyone else's thoughts, but mine are very simple. My primary rain gear is the Gatewood Cape. However, there's a couple of disadvantages of the cape, namely that your arms are still somewhat exposed if using trekking poles and you would be without rain gear while camping (answering the call of nature is one example of when this could be a problem).

However, my windshirt (GoLite Wisp) does the job for me for the most part. The DWR finish helps minimize how wet I get in both instances. Not only that, but it can help cut heat loss due to wind in colder weather. Not that I've really encountered colder weather yet (southwest Georgia), but it could happen :D

Tom

Yep, as a poncho-tarp fan I'd say a windshirt is usually critical. But…

"Are they neccesary for a long thru hike?"
Depends on which trail, and what your starting/ending dates are. I've noticed that a lot of people in the no-windshirt camp are AT hikers. In mostly low-lying areas, in moderate weather, I can see that. Especially at a moderate pace.

But IME, even an eVent jacket with pit zips is not comfortable enough to replace a windshirt in 3-season weather. Mainly it's a breathability issue, but the feel of the fabric has a lot to do with it to. I swear by windshirts (Lite Speed and Houdini for me) in all but the hottest weather – pretty much regardless of my shelter and raingear choices.

In addition to the usual reasons for using a windshirt, I've also found my windshirt(OR Ion) to be a valuable component of my sleep system. It has allowed me to get away with a WM Highlite(recently replaced by a Summerlite as a concession to age) well into September in the Sierra, most years, by slowing down heat loss without the annoying bulk of a rain shell inside a sleeping bag.

Thank you, these posts have been and will be very helpfull.

Windshirts are great. I made thru-hiker.com's Liberty Ridge in 1.1oz DWR and then in 1.1 oz teflon DWR, with full molded tooth zip and hood. It's pretty much the first thing to come with me after clothing worn. But then again, I am living in the San Juans, I could see how some get by without on the AT.
Mark Twight in Extreme Alpinism recommends in cold weather using a breathable windcoat over a base layer as a semi-permeable vapor barrier. You know how when you stop in the winter or take off your pack, and get cold, it can be from the clothing wicking too well (evaporation is a cooling process), so the windcoat slows it down a little and can keep you warmer. That's on my list of theories to test this winter.