
Easily the warmest jacket here, the Incandescent is literally stuffed with primo 800-fill down, but it’s still compressible enough to pack into its own pocket, making it great for overnight winter excursions. 1 lb
Instead of down or synthetic insulation, the Aire (like the SmartWool jacket) is stuffed with wool batting. It’s as toasty as a synthetic jacket of the same weight but will keep you warm when wet. 12.3 oz
The elastic wrist gaiters on the 850-fill Hadron are a smart and simple way to seal in heat. Plus, without a zipper, the pullover is ultralight and layers well under a shell. It packs down to the size of a softball. 7 oz
Holes in the jacket’s inner fleece trap heat when you need it. When you don’t, and you crack the front ventilating zips in the ripstop shell, they help the jacket transfer heat away from your body. It works—for the most part. The H2 Flow is great when you’re moving quickly (snowshoeing, backcountry skiing), but it’s a midlayer at its best on colder days. 15.4 oz
This slim-fitting, urban-styled jacket is warmer than it looks. Credit the 625-fill duck down, heavy-duty knit cuffs that keep out drafts, and burly DWR-coated polyester and cotton exterior. The Polartec soft-shell hood is removable. 2.5 lbs
Half fleece, half puffy—this insulating midlayer doubles as a full-on jacket, thanks to PrimaLoft insulation and a water-resistant, recycled-polyester shell around the chest. The arms and midsection are covered in Patagonia’s R2 fleece, which helped the Nano vent heat during morning skins. 11.4 oz