For the ultimate breathable windbreaker, look no further than the Smartwool Merino Sport Ultra, our Top Pick for Running. This thin, lightweight jacket has integrated mesh panels in strategic areas to help let off steam even when you're working up a sweat. Additional vented holes around the fronts and backs of the shoulders create even more airflow to keep you moving. It also features a high amount of reflective material in its construction - a must for low-light runners. However, with all that sweat, you'll need to wash the funk out of this jacket frequently. Its increased breathability also comes with lowered wind resistance and a pretty unimpressive water repellency. But if you need top-notch breathability for running through the gales, this is a great choice.
Smartwool Merino Sport Ultra Light Hoodie - Women's Review
Compare prices at 2 resellers Pros: Super breathable, comfortable, convenient pockets, great reflectivity
Cons: Stinks easily, gets wet quickly
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Our Analysis and Test Results
The Smartwool Merino Sport is a full-zip windbreaker with a hood, made of 100% nylon with 54% merino wool/46% polyester panels and lining. It's cut in a regular fit, has 2 zippered hand pockets, and features a reflective back panel and headphone wire hole in the right pocket.
Against so many seriously competitive windbreakers, the Merino Sport isn't particularly impressive when it comes to blocking the wind. The nylon sections (which comprise most of the jacket) are thin but offer reasonable wind protection. Even the zipper has a storm flap to back it up. However, the numerous vents and breathable mesh panels do just as good a job letting cold air in as they do letting hot air out. If you're heading out on a chilly day with a stiff breeze for a slow walk, we don't recommend this jacket. However, if you're out the door on a high-octane adventure, we think the sacrifice in wind resistance is worth the breathability you crave when you're covered in sweat.
Rather than have any adjustable points, the Merino Sport cuts all those extras out and replaces everything with elastic. The entire hem is lined with elastic, the cuffs are half-elastic, and even the back of the hood is pulled tight with a band of elastic. This certainly cuts down both on weight and on pieces jiggling around as you jog. While we appreciate this simplicity for a run, we wish we could have more control over each opening during regular wear. The one place where Smartwool added an extra feature to block the wind is the storm flap behind the main zipper. However, this storm flap is by far the most annoying one we tested and gets caught in the zipper repeatedly as you try to put it on.
Having made the trade-off in wind resistance to incorporate mesh panels and vents, the Smartwool is impressively breathable. This jacket is designed with the sweating human in mind, as breathable part-wool-part-polyester (54% and 46%, respectively) panels are strategically placed in the places you tend to sweat the most - your underarms and upper back. In addition to these "body-mapped mesh zones", large sections on the fronts and backs of the shoulders are opened to create vents through the coat that waft cool air in as you run.
The interior of the coat is also comprised of that same wool-polyester blend. Wool is a well-known regulator of body temperature, which once again comes in handy while you warm up, sweat, and cool down. However, the polyester portion of this blend seems to enjoy holding onto body odors. After even just a single run on a chilly day, this jacket smelled so rank that our main tester couldn't even bring herself to put it back on for another run. We also think that the cuffs are a little less comfortable than we'd like, especially for a running-focused jacket that's likely to have the sleeves pushed up on a regular basis. Only the bottoms are ridged from the elastic inside (the tops are smooth), but those ridges are particularly uncomfortable for long periods of time. With those minor complaints aside, the Smartwool is one of the most breathable windbreakers we tested.
Weight and Packability
Weighing just under 5 ounces, this jacket packs easily into its right, hand pocket with plenty of room to spare. Despite the zipper itself being fairly narrow, the pocket is nice and large. Even packed up, it can easily be compressed further and squished into a pack or purse. It also has a carabiner loop to hang from the outside of your pack, though it's a bit too large to be convenient that way. On the light end of the scale of windbreakers we tested, this jacket feels quite light to wear - a big plus for a running jacket.
The nylon portions of the jacket also boast a fine ripstop pattern to help the Merino Sport last longer, which is essential for something you're expected to compress repeatedly for years on end. However, its stitching is minimalized to cut down on weight as well, which makes the jacket a bit frailer overall.
The Smartwool has a lot of features that make it a great windbreaker for running and other high output sports. A huge panel across the back is crisscrossed with reflective stripes to increase your visibility in low light conditions. Each sleeve also boasts a 4-inch reflective strip near the wrists for added visibility from oncoming traffic. The vents and mesh paneling discussed previously are also a great help for a sweaty body. A lack of toggles anywhere keeps the whole jacket light and easy to forget you're wearing.
Unlike many windbreakers, that cut out hand pockets to decrease weight, the Merino Sport has two good-sized zippered hand pockets that easily fit any smartphone. The right pocket also has a small hole at the top on the inside to let the cord from a pair of headphones snake through it. Those large hand pockets also form pseudo-pockets inside the jacket, as you can slip something between the pocket and the coat itself. However, they're not true pockets, because a 2-inch section at the bottom is left open for drainage, which lets smaller objects slip right out.
Smartwool advertises that the Merino Sport "works even better when worn in layers" and we'd have to agree - to a point. We really appreciate this super breathable, lightweight shell over a long-sleeved shirt (over a tank top) when heading out for a run on a breezy spring afternoon. However, its regular, slightly athletic fit isn't quite as ideal over a bulky fleece layer or thin puffy jacket. As far as windbreakers for high output activities go, we think this one is a pretty solid choice, but it lacks some of the style and versatility we're looking for in a windbreaker that can take you from the trails to the office.
This is one metric where we aren't impressed by the Smartwool Merino Sport. Though it's treated with a DWR finish to help repel moisture, that protection is very limited. In a light rain, the first droplets bead up on the outside of the jacket. However, the longer they sit there, the more likely they are to soak into the fabric. In moderate rain, we got wet in just a few short minutes. During our intense water testing, where we leave a puddle of water sitting on each jacket, the Merino Sport was saturated within just a couple of minutes.
The mesh sections are even worse at repelling water, and instead, soak it up almost immediately. While you'd hope these sections will see less rain (in your underarms and between your shoulder blades), they are a very weak spot in any precipitation - and also soak up that smelly sweat along the way. Additionally, any jacket treated with a DWR coating needs to be regularly replenished with a special treatment (like Nikwax) in your washer at home. The more often you move in and wear a garment, the quicker the DWR coating wears off. If you wash it for any other reason, that also wears on the DWR coating. And since this running windbreaker tends to become stinky quickly, that's more washes and less DWR coating for when you really need it.
The Merino Sport falls about in the middle of the pack for the price. When it comes to value, that really depends on your intended use. If you want a windbreaker that excels during casual strolls on cold days or functions as a reasonably professional layer to throw on over your collared shirt for work, this might not be the most ideal choice. However, if you're after a super breathable windbreaker for high output activities, we think this one is an exceptional value for its performance.
When it comes to running on a windy day, there's no other windbreaker we reached for more than the Smartwool Merino Sport. Its combination of impressive breathability, light weight, and comfortable feel makes this jacket our Top Pick for Running.
— Maggie Brandenburg