If you need a jacket to wear when conditions are so cold that a midlayer alone won’t cut it, you need insulated outerwear. Consider two primary factors as you choose:

• Insulation Type: This key component of your jacket determines how well it retains warmth and handles wet conditions, as well as how small it will pack. How active and sweaty you plan to get is also a factor in insulation choice.
• Jacket Features: Hoods, adjustments, vents, pockets and special features like powder skirts all affect comfort and convenience.

Other considerations include weight and materials:

• Weight and compressibility are important for any activity where you’ll be carrying the jacket in your pack.
• Shell materials affect rain protection, breathability, mobility, durability and a jacket’s ability to fend off windchill.

Alternative jackets:

Men’s ski and snowboard jackets and women’s ski and snowboard jackets include special features like powder skirts that make them well suited for those sports.

Men’s fleece and soft-shell jackets and women’s fleece and soft-shell jackets are options for less severe conditions.

Why no temperature ratings? A jacket rated to be warm at a given temperature in dry, still air isn’t likely to keep you warm at that same temperature in a howling wind or dank, foggy conditions. It’s not possible to account for variables like wind, rain, humidity, exertion level and personal metabolism. Thus any temperature rating on a jacket would be incorrect most of the time. 

Insulation Types

Nature’s best insulator, these plumules from ducks and geese provide the most warmth for the least weight and bulk—just as long as you don’t get the down wet. The main benefits of down are the fact that it is ultralight, ultrawarm and ultrapackable. On the other hand, it won’t insulate when damp and dries slowly. If you anticipate rain, snow, humidity or being active enough to break a sweat, you should look at water-resistant down, synthetics or down/synthetic hybrids. One way to determine the quality of down is to look at its fill power. Ranging from about 450 to 900, fill power is the volume in cubic inches that one ounce of the down fills up; higher quality down lofts to a higher volume, so a higher spec number indicates warmer down.

Water-Resistant Down

Polymer treatment helps water-resistant down handle dampness and it’s just as light as regular down. Like down, it’s ultralight, ultrawarm and ultrapackable. The negatives? It’s pricey and wet performance lags behind synthetics.

Synthetic Insulation

Available in a vast range of branded technologies, all synthetics use some form of compressible water-repellent fibers. Innovation is rapid and the performance gap with down is shrinking. Note that “puffiness” is not indicative of synthetic jacket warmth—superfine fibers in the insulation can create slim-yet-warm jackets.

The main benefits of synthetic insulation are that it performs when damp, dries fast and is usually more moderately priced than down. However, it’s a little heavier and less packable than down and a little less durable.

Numbers like 40g or 60g on a synthetic fill state the weight in grams of a square meter of that insulation. A higher number tells whether it’s a thicker, and therefore warmer, application. This spec is only useful in comparing warmth between identical types of insulation.

Activity level: Can handle strenuous exertion

Down/Synthetic Insulation

This approach offers a mix of the performance benefits of each type of insulation. Some designs blend the down and synthetic fills together and use that blend throughout the jacket. Some designs put down in some areas, like the core, and synthetics in other areas, like the arms or sides. Another plus: If you’d love to get a down jacket but are constrained by your gear budget, hybrid fills help keep costs lower.

Activity level: Can handle strenuous exertion

Wool/Synthetic Insulation

A few brands combine wool with a synthetic material to create sheets of insulating fill. Jackets that use this blend benefit from wool’s ability to insulate when damp and its resistance to odor.

Activity level: Can handle strenuous exertion

Jacket Features

3-in-1 Design

This design has an integrated midlayer and outer shell that zip together or attach via a few tabs. The beauty of this setup is that it allows you to wear the midlayer alone, the outer shell alone, or both pieces together—hence the 3 options. The insulation in the midlayer will vary from the insulations discussed here to a fleece or wool liner jacket. The outer shell will be water resistant, or offer full-blown waterproof/breathable coverage.

Waterproof Construction

Because water can impair insulation performance, especially in untreated down, the outer shell of an insulated jacket is water resistant. Some insulated shells go further, having a waterproof/breathable exterior fabric, along with taped seams. Though this type of insulated shell is more expensive, it will be comparable in price to a 3-in-1 jacket. It also means you won’t have to buy and pack a separate rain shell.

Hood

People who prefer a hoodless jacket like the weight savings and packing ease it provides. They simply pack a winter cap along for colder conditions. Some hoods are detachable or will zip inside the collar. A few hoods are insulated for added warmth. If you’re a climber, you need a “helmet compatible” hood to ensure it’s big enough to fit over a helmet. Nonclimbers sometimes avoid this feature because it makes the hood a little unwieldy.

Adjustment Features

• Hood adjusters are usually on the sides, with another in back. Some hoods use elasticized trim instead to create a sleek, though less precise fit.
• Drawcord: Typically at the bottom hem, it blocks wind and cold air. A few jackets have the drawcord at the waist instead.
• Front zipper: Most have a chinguard on top and a storm flap in front; some jackets save weight and bulk by having a water-resistant zipper instead of a storm flap. A few longer urban jackets might have a two-way front zip that lets you adjust the bottom opening for walking or sitting.
• Cuffs: Most have Velcro tabs that make it easy to adjust wrist fit, sealing out wind and cold air. Some jackets use an elasticized trim instead, which offers less bother and bulk, but also a less precise fit.

Pocket Features

Having more pockets offers added storage, but it also adds weight and bulk, and ups the price of the jacket. Zip, snap or Velcro closures offer more secure storage, though an open pocket offers fast access.

• Zipper protection: For added rain protection, exposed pockets on some jackets might have flaps; other jackets use water-resistant zips to eliminate bulky flaps.
• Hipbelt compatibility: Having pockets set slightly higher ensures you access to them while wearing a pack hipbelt.
• Music pockets: Found more often in urban jackets, these have a port inside for routing headphone cords.
• Security pockets: Found more often in travel jackets, these are inside the jacket and/or have a hidden zip opening along a seam or under a flap.
• Drop-in pockets: Handy for quickly stashing a hat or gloves, these large open pockets are inside the jacket, directly behind the side pockets.

Vents

Though found primarily on rain jackets, a few insulated jackets also include underarm vents and/or core vents that are handy when your exertion level rises. You’ll find vents more often when a jacket has a waterproof/breathable shell.

“Body-Mapped” Design

A growing trend is to vary the insulation and shell material based on where it sits on your body. Stretch side panels, less bulky insulation on the sides, waterproof upper surfaces and windproof front panels are just a few examples of this kind of adaptation. The benefit is more refined performance for an intended activity. You won’t find a single term to describe this design approach. It should be easy to spot, though, as you read product descriptions.