Mountain Warehouse Summit 250 Sleeping Bag Review (2025): Budget 3/4‑Season Synthetic That’s Better Than You Expect

Looking for a cheap, dependable synthetic bag that won’t freak out when it’s damp? The Summit 250 is Mountain Warehouse’s workhorse: a 3/4‑season bag with a comfort window of about −1 °C to 4 °C and an extreme rating of −17 °C (survival only, not a target). It’s a mummy‑shaped, hollowfibre bag with a ripstop polyester shell, a two‑way zip for venting, and the neat ability to zip left+right bags together for a double.

Looking for a cheap, dependable synthetic bag that won’t freak out when it’s damp? The Summit 250 is Mountain Warehouse’s workhorse: a 3/4‑season bag with a comfort window of about −1 °C to 4 °C and an extreme rating of −17 °C (survival only, not a target). It’s a mummy‑shaped, hollowfibre bag with a ripstop polyester shell, a two‑way zip for venting, and the neat ability to zip left+right bags together for a double.

What’s actually true about warmth

Use the comfort range (−1 to 4 °C) as your guide and ignore “extreme” unless you like shivering. To hit those numbers, pair the bag with an insulated sleeping pad (R‑value ≈ 3–4+) and dry base layers. In calm conditions the Summit 250 feels secure on frosty shoulder‑season nights; in exposed, windy sites you’ll want extra clothing or a warmer bag.

Size, weight & packability

Expect ~1.4 kg (Regular) or ~1.6 kg (Long) and a packed size around 22 × 40 cm. That’s fine for car camping and short walks in—but bulky for lightweight backpacking. If pack space is tight, look at a true three‑season down bag or a higher‑end synthetic that compresses better.

Details that matter in use

• Cut & variants: The Blue Teal model is typically mummy‑cut with a hood; some retailers also sell a Square Summit 250 with more leg room and similar insulation.
• Fabric & fill: Polyester ripstop shell, polyester lining, and hollowfibre insulation tolerate damp and are easy to sponge‑clean.
• Hardware: Two‑way, full‑length zip with storm flap for venting; twinable if you buy opposite‑hand zips.
• Lengths: Regular ~200 cm (max user height ~180 cm); Long ~215 cm (max ~195 cm).

Who it’s for

Budget‑minded campers, festival‑goers, and youth trips who want a warm‑enough, low‑maintenance bag for spring through autumn. It’s also a good loaner/spare for friends who show up under‑prepared.

Who should skip

Weight‑sensitive backpackers, winter campers, and anyone routinely sleeping below freezing. You’ll fight the bulk and run out of warmth margin.

Pros

• Genuine cold‑weather usability for the price (comfort −1 °C to 4 °C).
• Durable, easy‑care fabrics; synthetic fill shrugs off damp.
• Two‑way zip + twinable design add flexibility for venting and doubles.

Cons

• Bulky and relatively heavy versus premium three‑season bags.
• Compression sack quality varies; many owners upgrade the stuff sack.
• Comfort claims depend on pad/clothing; extreme rating is survival‑only.

Bottom line

If your priority is price + reliability, the Summit 250 is a sensible pick for cool‑weather car‑camping and general use. Treat the −1 °C to 4 °C comfort window as honest, plan your sleep system accordingly, and you’ll get a lot of nights out of a little money.

Where to Buy

• Amazon