Arc'teryx Atom LT
The Arc'teryx Atom LT works best as a breathable midlayer for active outdoor use between 20 and 45°F. Its key advantage over competitors like the Patagonia Nano Puff is superior breathability from stretch fleece side panels, making it ideal for hiking and snowboarding when you're generating heat. At 375 grams with 60g/m² Coreloft insulation, it balances warmth and ventilation better than fully-insulated alternatives.
I take this on every snowboarding trip as a midlayer option under my shell jacket. When temperatures drop and my fleeces aren't enough, the Atom LT goes under my shell. For backcountry tours, it works as a warming layer for the skin track, then gets stashed before descending. It's what I grab when I'm not sure what conditions I'll face.
Does the Arc'teryx Atom LT Work for Hiking?
Yes, but with specific temperature limits. This jacket performs well on cool trails between 25 and 45°F when you're moving continuously. The stretch fleece side panels prevent overheating during ascents, a feature that fully-insulated jackets can't match. I wear a merino base layer underneath when temperatures drop to 30°F. Below 25°F, you'll need something heavier like the Atom AR.
The fit allows unrestricted arm movement for scrambling or using trekking poles. Hem adjusters actually work and stop cold air from sneaking up when you're standing on windy summits. The elastic cuffs seal against your wrists without cutting off circulation.
Arc'teryx Atom LT vs. Patagonia Nano Puff
Arc'teryx uses a hybrid insulation approach. The torso and arms get Coreloft Compact 60g/m² synthetic fill, while sides and underarms use stretch fleece panels instead. This design breathes better than the Patagonia Nano Puff, which insulates evenly throughout.
The Nano Puff costs about $100 less and feels slightly warmer when you're stationary. But if you run hot or plan to wear your jacket during activity, the Arc'teryx's breathability makes more sense. Durability favors the Atom LT too. The 20-denier Tyono face fabric with DWR treatment holds up better when worn with a backpack or brushed against rock.
Best Between 20 and 45 Degrees
The Atom LT handles 20-45°F depending on activity level and what you're wearing underneath. Below 20°F, you need more insulation. Standing around at 15°F in just the Atom LT won't cut it. Above 45°F during active use, this jacket gets too warm. The fleece panels help dump heat, but there's only so much they can do.
Wind resistance is solid. The DWR-treated shell blocks enough wind to prevent heat loss on exposed ridges or chairlift rides. Not a hardshell, so don't expect it to stop sustained wind, but it handles breezy conditions without issue. For full weather protection, layer this under a Beta SL Jacket.
Two Seasons and Still Holding Up
After two seasons and probably 15 washes, I haven't seen any zipper failure or cuff stretch. The Coreloft insulation doesn't clump like some synthetic fills when you wash it. The DWR coating wears off over time where pack straps contact the fabric, but I re-treat mine once per season with Nikwax. Machine wash cold, tumble dry low.
The jacket comes in hooded and non-hooded versions. I chose the hooded model because it adds warmth and protection without much weight penalty. The hood fits under a helmet for skiing or over a beanie for hiking. For other jacket options, see the jacket list.
Specs and Colors
Weight: 375 grams (13.2 oz) for men's medium
Materials: 20D Tyono shell with DWR, Coreloft Compact 60g/m² insulation, stretch fleece side panels
Features: Two handwarmer pockets, internal chest pocket, adjustable hem, elastic cuffs
Colors: Stingrey, Proteus, Vermillion, Toreador, Pilot, Ember, Trail Blaze, Yukon, Woad, Wheatgrass, Silverstone, Shimizu, Yugen, Tui, Flux, Tungsten, Deep Dusk, Emerald Isle, Chipolte, Tobiko, Platinum, Kodiak, Thalo, Echo Blue, Oxblood, Phoenix, Poseidon, Sodalite, Kyanos, Dracaena, Paradox, Dynasty, Galactica, Squid Ink, Rhapsody, Kingfisher
Price: ~$300
At just over 6 feet and 165 pounds, I wear a medium. Check current availability at Arc'teryx.