Western Mountaineering SummerLite Sleeping Bag - 0°C Down Bag (Ultralight 3-Season, 850+ Fill)

Ultralight Freedom Without Compromise

The Western Mountaineering SummerLite is one of the lightest fully-featured sleeping bags available, designed for climbers and backpackers who want true ultralight performance without sacrificing functionality.

Weighing just ~540g, it features a fully baffled construction, full-length zip, and insulated draft tube-delivering reliable warmth down to 0°C while remaining incredibly compact and packable.

Built with 850+ fill power goose down and a lightweight shell, the SummerLite is the perfect companion for fast-moving adventures and lightweight backcountry travel.

Why You'll Love It

Ultra-lightweight - From ~510g
Full-length zip - More versatility than most ultralight bags
850+ fill power down - Premium insulation
Compact pack size - Easy to carry
Fully baffled - Better warmth control

Built for Lightweight 3-Season Adventures

Perfect for:

Backpacking
Thru-hiking
Alpine climbing
Summer and shoulder-season use
Fast & light missions

Designed for those who want lightweight gear without compromise

Performance Features

Lightweight 3-Season Warmth (0°C)

Reliable performance

Keeps you:

Warm in mild to cool conditions
Comfortable in changing weather
Prepared for shoulder-season nights

850+ Fill Power Goose Down

Premium insulation

Provides:

High warmth-to-weight ratio
Excellent compressibility
Long-lasting loft

Continuous Baffle System

Adaptive insulation

Allows:

Shifting down for colder nights
Balancing warmth in milder temps
Greater versatility

Full-Length #5 YKK Zipper

Enhanced usability

Allows:

Easy entry/exit
Full ventilation
Use as a blanket when open

Insulated Draft Tube

Heat retention system

Helps:

Block cold air
Maintain warmth
Improve efficiency

Lightweight Shell Fabric

12D ripstop nylon

Benefits:

Low weight
High packability
Durability for its class

Technical Specifications

Temperature Rating: 0°C
Fill: 850+ Fill Power Goose Down
Loft: 10 cm (4")

Weights:
165cm: 510g
180cm: 540g
200cm: 595g

Fill Weights:
165cm: 225g
180cm: 255g
200cm: 285g

Girth (Shoulder/Hip/Foot):
165cm: 150 / 130 / 97 cm
180cm: 150 / 130 / 97 cm
200cm: 152 / 132 / 97 cm

Packed Size:
All sizes: 15 x 30 cm

Origin: USA

Includes:
Ultralight stuff sack
Breathable mesh storage bag

Perfect For

Backpackers
Thru-hikers
Alpine climbers
Lightweight travellers
3-season adventurers