Best sleeping bags for cold nights & power cuts (2026)
A proper sleeping bag is the most effective way to stay warm through a cold night with no heating — a winter power cut, a draughty house, or camping. It traps your body heat far better than piling on blankets, and the right one keeps a person genuinely warm down to freezing and below. Here's how to read the ratings and choose.
By Tom Rowland · Updated 18 July 2026 · 5 products, price-tracked
Before you buy
Read the temperature rating properly. Sleeping bags are rated (often to the EN/ISO 23537 standard) with a 'comfort' figure — the temperature at which a cold sleeper stays warm — and a lower 'limit' figure for a warm sleeper. Use the COMFORT rating, and give yourself margin: for a UK winter power cut indoors, a comfort rating around 0°C to -5°C covers a genuinely cold night with room to spare.
Choose fill by use. Synthetic bags are cheaper, keep insulating when damp, and are the sensible choice for home emergency use and general camping. Down bags are warmer for their weight and pack far smaller, but cost more and lose loft if they get wet — worth it if you backpack or need compactness, overkill for a bag that lives in a cupboard for a power cut.
Then shape and extras: a mummy shape with a hood traps the most heat (a lot escapes from your head), while a rectangular bag is roomier and can double as a duvet. A draught collar and a well-filled zip baffle stop cold spots. For storage, keep it loosely in the large sack it came with, not compressed, so the fill keeps its loft.
Top pick: Snugpak Softie 9 Hawk Sleeping Bag. A dependable, UK-made synthetic bag whose insulation keeps working even when damp, making it a sensible choice for an emergency kit or an unheated home during a winter power cut. It is heavier and bulkier than a down equivalent, so it earns its place in the car boot or a cupboard rather than a lightweight hiking pack.
| Bag | Comfort temp | Season rating | Fill | Weight | Price | |
|---|---|---|---|---|---|---|
| Snugpak Softie 9 Hawk Sleeping BagTOP PICK | -5 °C | 3-season (4 with liner) | Softie Premier synthetic insulation | 1,500 g | £129.00at usual price | Check price → |
| Rab Ascent 500 Down Sleeping Bag | 1 °C | 3-season | 650 fill-power hydrophobic duck down (500g) | 1,060 g | £210.00at usual price | Check price → |
| Snugpak Jungle Bag Sleeping Bag | 7 °C | 1-season (warm/tropical) | Travelsoft synthetic (polyester) | 900 g | £40.00at usual price | Check price → |
| Vango Atlas 350 Sleeping Bag | 2 °C | 3-season | Synthetic (hollowfibre/polyester) | 1,550 g | £32.00at usual price | Check price → |
| Mountain Warehouse Microlite 950 Sleeping Bag | 5 °C | 3 season | Microfibre (synthetic polyester) | 1,400 g | £35.00at usual price | Check price → |
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Snugpak Softie 9 Hawk Sleeping Bag
Who it's for: A warm, damp-tolerant bag for a home or car emergency kit and cold-weather use.
A dependable, UK-made synthetic bag whose insulation keeps working even when damp, making it a sensible choice for an emergency kit or an unheated home during a winter power cut. It is heavier and bulkier than a down equivalent, so it earns its place in the car boot or a cupboard rather than a lightweight hiking pack.
- Synthetic Softie insulation still warms when damp, a real advantage over down for home and car emergency use
- Genuinely warm to around -5C comfort, enough to see out a UK winter power cut rather than just mild nights
- Solidly built and made in the UK, with a two-way anti-snag zip, reinforced foot and compression stuff sack
- At about 1.5kg and a fairly bulky pack size, it is heavy compared with down or lightweight bags
- Costs more than budget synthetic bags of similar temperature rating
Don't buy if You mainly need a light bag to carry far on foot, or only ever camp in mild summer weather, where a lighter and cheaper bag will pack smaller and serve you better.
Rab Ascent 500 Down Sleeping Bag
Who it's for: Three-season UK camping and a warm, packable down bag to keep in a cold-weather grab kit.
A well-built, genuinely warm three-season down bag with a tough shell and a hydrophobic finish that copes with British damp. Sensible if you want lasting quality, though it is being phased out, so check availability before setting your heart on it.
- Comfort rating of about 1°C gives real three-season warmth for UK spring, summer and autumn nights
- 650 fill-power down with a Nikwax hydrophobic treatment resists the damp better than untreated down
- Hard-wearing outer fabric and thoughtful details (draught collar, zip guard) stand up to regular use
- Packs down small and stays light for a down bag at around 1,060g
- Down still loses warmth if it gets thoroughly wet, so it needs more care than a synthetic bag
- Premium price for the warmth, and stock is patchy now the model is being discontinued
Don't buy if You mainly want a cheap bag to keep by the bed for a winter power cut or one that might get soaked; a synthetic bag holds its warmth when damp, costs less and is the more sensible choice there.
Snugpak Jungle Bag Sleeping Bag
Who it's for: A light, tiny-packing summer bag for warm-weather trips or the milder half of a grab-bag
A well-made British warm-weather bag that packs down remarkably small and adds a handy zip-over mosquito net. It is genuinely good at its job, but that job is comfort down to about 7°C, not cold-weather survival.
- Very small pack size and light (about 900g) for a square-cut bag, so it slots easily into a grab bag
- Roll-away mosquito net in the hood and a square shape that opens flat into a quilt for versatility
- Snugpak build quality and UK support at a modest price
- Comfort rating of only about 7°C means it is a warm-weather bag, not a winter one
- Square foot and single-season fill trade a little thermal efficiency for room to move
Don't buy if Do not buy this expecting it to keep you warm through a winter power cut or a cold night below single figures. For year-round emergency warmth choose a 3-4 season bag; keep the Jungle Bag for summer use or as a packable warm-weather layer.
Vango Atlas 350 Sleeping Bag
Who it's for: An affordable, warm-enough 3-season bag for a grab bag or occasional cold nights.
A sensible, budget-friendly synthetic bag that is EN-tested comfortable to around 2°C and machine washable, which makes it easy to keep in a cupboard for emergencies. It is not a deep-winter or lightweight backpacking bag, but for household preparedness at this price it is honest value.
- Low price for an EN ISO 23537 comfort rating of about 2°C
- Synthetic fill copes better with damp than down and is machine washable
- Hooded mummy shape with drawcord seals in warmth on cold nights
- At roughly 1.55kg and bulky, it is heavier and less packable than down alternatives
- Comfort only to about 2°C, so it will feel cold in a genuinely freezing, unheated home
Don't buy if Don't buy if you need reliable sub-zero winter warmth or an ultralight bag for carrying long distances; choose a warmer 4-season or a down bag instead.
Mountain Warehouse Microlite 950 Sleeping Bag
Who it's for: An affordable, machine-washable synthetic bag to keep in a home grab-bag or car for cool-weather standby.
A budget-friendly 3-season synthetic bag that offers reasonable warmth and easy care for the price. It is a practical home-standby or car-camping bag rather than a lightweight or genuine winter option.
- Low cost and widely available in the UK, so easy to buy a spare or two for a household kit
- Synthetic microfibre fill keeps insulating even if it gets damp and is machine washable
- Left/right-hand zip versions can be joined into a double, useful for a family kit
- At around 1.4kg and bulky when packed, it is heavy for backpacking and better suited to the car or a cupboard
- The comfort rating is optimistic — many users find it sleeps cooler than the label, so add a liner for colder nights
Don't buy if Don't buy this if you need a genuine lightweight backpacking bag or reliable sub-zero winter warmth — this is a value standby bag, not a technical cold-weather one.
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Common questions
What temperature sleeping bag do I need for a UK winter?
Go by the comfort rating and allow margin — a comfort figure around 0°C to -5°C keeps an adult warm through a cold British night indoors with room to spare. The 'limit' rating is for a warm sleeper and shouldn't be your target.
Down or synthetic sleeping bag?
Synthetic is cheaper and keeps insulating even when damp, making it the sensible choice for home emergencies and general camping. Down is warmer for its weight and packs smaller, but costs more and loses warmth if it gets wet — best for backpacking.
Is a sleeping bag better than blankets in a power cut?
Yes — a sleeping bag traps your body heat far more efficiently than layered blankets, especially a mummy bag with a hood that stops heat escaping from your head. It's the most effective way to stay warm through a cold night without heating.
What does the season rating mean?
It's a rough guide: 1–2 season for summer, 3-season for spring and autumn, and 4-season for winter. Treat it as a starting point and check the comfort temperature, which is the more precise measure of warmth.
How should I store a sleeping bag?
Loosely, in the large storage sack it came with, rather than crammed in its compression stuff sack. Keeping the fill uncompressed preserves its loft, which is what keeps the bag warm over the years.
Do I need an expensive sleeping bag for a power cut?
No — a mid-range 3-season synthetic bag keeps an adult warm indoors through a cold night cheaply. Spend up for a down or 4-season bag only if you also camp, backpack, or need to save weight and pack size.