When Should You Switch To A Winter Duvet? Data Reveals The Cosy Cut-off Point

Every September, as the evenings draw in and that first crisp breeze finds its way into our bedrooms, the same question arises: when is the right time to pack away the summer quilt and snuggle under a winter duvet?

It is the point in the year when fluffy socks reappear, hot water bottles are pulled out of cupboards, and beds across the country begin to feel less like a summer sanctuary and more like a chilly reminder that autumn has arrived.

To move beyond guesswork, we’ve analysed temperature data across the UK’s 50 most populated towns and cities to reveal exactly when the thermometer dips low enough to justify thicker bedding.

The findings show that September is duvet season for most of the UK. While the exact date varies from place to place, the majority of households will need thicker bedding before the end of the month, with many already experiencing single-digit nights.

Why 10°C is the Magic Number for Switching to a Winter Duvet

At MattressNextDay, we use 10°C as the tipping point for when households should think about swapping to a winter duvet. But why does this number matter?

Many scientific studies have shown that our bodies are very sensitive to the temperature of our surroundings at night. The ideal bedroom environment for restorative sleep usually sits between 16 and 18°C. Once outdoor night-time temperatures fall below 10°C, many bedrooms without heating naturally drop outside of this comfort zone, leaving sleepers at risk of feeling the chill.

When the room is too cold, your body works harder to regulate its core temperature. This can mean:

• Waking up during the night as your body reacts to the cold.
• Restless movements that reduce the time spent in deep sleep.
• Feeling sluggish in the morning, even if you were in bed for a full eight hours.

A thicker duvet creates a consistent cocoon of warmth, helping your body stay balanced. It prevents unnecessary sleep disturbances and allows you to fall into the deeper, more restorative stages of rest.

This is why the 10°C mark is a useful guide for households across the UK. It is the point where nights are cool enough to disturb sleep, and where making the switch to a winter duvet can transform the way you feel in the morning.

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Uncovered: The UK’s Duvet Switch Dates

So, when does the temperature tell us it is time to change the bedding? Using average minimum night-time temperatures, we identified the exact point each of the UK’s 50 most populated towns and cities falls below 10°C.

The results stretch from mid-August in Aberdeen and Swindon through to early October in Swansea. For most locations, though, the switch comes during September, confirming its role as the UK’s true duvet season.

Here is the full breakdown city-by-city:

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The Great British Duvet Divide

Much like the debate over how to pronounce scone, our findings reveal that the UK is far from united when it comes to duvet season. In some towns and cities, residents should have made the switch to a thicker quilt in August, while others can comfortably hold off until October.

Northern cities feel the chill first

It is no surprise that cooler nights arrive sooner in the north, but the exact dates tell the real story. Leeds, Newcastle and Manchester have already slipped below the 10°C mark, meaning households there should be sleeping under winter duvets by now.

The very first city to feel the change was Aberdeen, which dropped into single figures on 16 August. More unexpectedly, Swindon in the South West recorded the same date, despite being almost 500 miles away.

For households here, the lighter summer quilt may already be folded away for the season, replaced with something heavier to keep out the chill.

97% of the country will need to switch by the autumn equinox 

September does not leave much wiggle room. By the time the autumn equinox arrives on 22 September, which marks the end of summer, 47 out of the 50 locations in our study will already be shivering through nights below 10°C.

That means 97% of the UK population will be reaching for a winter duvet before summer has even waved goodbye.

Coastal towns can wait the longest

At the other end of the results is Swansea, which is not expected to fall below the 10°C mark until 3 October. Thanks to the sea’s ability to hold onto warmth, many coastal towns can keep their lighter bedding for a little longer than the rest of the country.

While Aberdeen households should have been under thicker quilts since mid-August, Swansea sleepers get almost seven bonus weeks with their summer bedding.

Six Simple Switches for Better Sleep This Autumn

As the nights cool and the evenings draw in, a few simple changes can turn your bedroom into the cosiest spot in the house. From picking the right tog to swapping your sheets, these switches will help you drift off more comfortably despite the cooler nights.

1. Pick the perfect tog

As nights dip into single figures, most households will feel comfortable with a duvet between 10.5 and 13.5 tog. This weight strikes the balance between cosy and breathable, giving you warmth without feeling too heavy. Our tog rating guide breaks this down further.

2. Layer smartly

Instead of relying on one thick quilt, try layering your bed with seasonal accessories. A soft blanket or throw can add warmth, while a mattress protector provides an extra insulating layer that also keeps your bed fresher for longer.

3. Keep your bedroom in the sweet spot

Bedrooms that sit between 16 and 18°C are shown to support the most restorative sleep. If your room is cooler, you may find yourself waking in the night. If it is warmer, you could struggle with overheating. A simple room thermometer or adjusting your bedding layers will help you stay comfortable.

4. Switch your sheets

Breathable cotton is perfect in summer, but as autumn arrives, fabrics like brushed cotton or flannel can make the bed feel more inviting. They add gentle warmth without locking in too much heat, creating that snug autumn cocoon. 

5. Add a cosy pre-bed routine

Little rituals like a warm shower, slipping into fluffy socks, or placing a hot water bottle at the foot of the bed can make a noticeable difference. By raising your body temperature slightly, you’ll find you drift off more comfortably once you are under the covers.

6. Check your mattress

Your duvet does the heavy lifting when it comes to warmth, but not many people are aware that your mattress plays a role, too. A quality mattress topper can add insulation, while an ageing mattress may no longer give you the support you need. If yours is more than eight years old, it may be time to consider an upgrade for comfort and health.

Martin Seeley, CEO at MattressNextDay, concludes:

While every city has its own date for switching to a winter duvet, our in-depth analysis makes it clear that September is when most of us should start preparing for cosier nights ahead.  The majority of UK towns and cities will have dropped below the 10°C mark before the end of the month, which is why September really stands out as the UK’s true duvet season. This is the time when lighter summer bedding starts to leave us restless and chilly, and when switching to a thicker quilt makes all the difference.  Making the change now means you will sleep more comfortably, wake up feeling refreshed, and set yourself up for healthier sleep right through to spring.

Methodology

To identify when households across the UK should switch to a winter duvet, MattressNextDay analysed data from the Met Office on average minimum night-time temperatures. We focused on the 50 most populated towns and cities to ensure the results reflect where most people live.

We then calculated daily changes in temperature by bridging the gap between monthly averages. This gave us a reliable estimate of the exact date each location would first fall below 10°C at night, which is widely recommended as the point to move from a summer quilt to a thicker winter duvet.

By applying this approach across every location, we created a clear picture of when each city is likely to need a winter duvet in 2025. The results range from early switchers in mid-August to coastal locations that can wait until early October.