What should a 3-month-old wear?
4 min read
Quick answer
A 3-month-old should wear one more layer than you, as the NHS suggests, matched to the temperature. For sleep, use a sleepsuit and an arms-out sleeping bag with the right TOG for a room of about 16–20°C. Stop swaddling as soon as your baby looks like they are trying to roll.
- Same temperature rules as younger babies
- Stop swaddling at the first signs of rolling
- Arms-out sleeping bag for sleep
- Check the neck or tummy, not their hands
What changes at 3 months
The way you dress for warmth stays the same. What often changes around this age is movement: many babies push up, kick hard and start trying to roll. The AAP advises stopping swaddling as soon as your baby looks like they are trying to roll over, which often happens around 3 to 4 months but can be earlier.
Babies also outgrow sleepsuits and sleeping bags quickly at this stage. Check that both still fit, using the size guide on the label, as you move up a size.
What should a 3-month-old wear outside?
Use the outdoor temperature, not the season. As a guide:
- 10–14°C (50–57°F): vest, sleepsuit, warm cardigan, pramsuit, hat and mittens
- 15–18°C (59–64°F): vest, sleepsuit and a cardigan or light jacket
- 19–21°C (66–70°F): vest and light sleepsuit, thin cardigan to hand
- 22–23°C (72–73°F): short-sleeved vest and light trousers or a romper, sun hat
- 24–26°C (75–79°F): single layer of lightweight cotton, wide-brimmed hat, shade
- 27–30°C (81–86°F): one thin cotton vest or romper, wide-brimmed hat, full shade
What should a 3-month-old wear to sleep?
For sleep, go by the room thermometer. NHS advice is a room of about 16–20°C, with your baby on their back in a clear cot in your room. As a guide:
- under 16°C (under 61°F): a vest plus a long-sleeved sleepsuit under a warm (2.5 to 3.5 TOG) sleeping bag
- 16–19°C (61–66°F): a long-sleeved cotton sleepsuit under a 2.5 TOG sleeping bag
- 20–23°C (68–73°F): a cotton sleepsuit (or long-sleeved vest) under a 1.0 TOG sleeping bag
- 24–26°C (75–79°F): a short-sleeved cotton vest under a 0.5 TOG sleeping bag
- 27°C+ (81°F+): a short-sleeved cotton vest, alone or under a 0.2 TOG sleeping bag
How to check your 3-month-old is not too hot or cold
Feel the back of your baby's neck, their chest or their tummy. Warm and dry means they are dressed right. Sweaty or hot means take off a layer of clothing or bedding. Cool hands and feet on their own are normal, so do not add layers just because fingers or toes feel cold.
Active babies can get warm and sweaty during floor play or a long feed. Check the back of the neck or tummy rather than their hands, and take a layer off if they are damp.
Moving from a swaddle to a sleeping bag
When you stop swaddling, an arms-out sleeping bag keeps your baby warm without loose blankets. A swaddle adds warmth, so when you switch you may need a slightly warmer bag or a vest under the sleepsuit, depending on the room.
Keep putting your baby on their back for every sleep in a clear cot, with a firm, flat mattress and no pods, nests, bumpers or pillows (NHS). Never use a weighted sleeping bag or swaddle (AAP).
This is general dressing guidance, not medical advice. If you are worried your baby is unwell, call NHS 111 or your GP. In an emergency, call 999 or your local emergency number.
Sources
We check this guide against these sources. It is general information, not medical advice: speak to your health visitor, GP or paediatrician about your own baby.
Questions parents ask
Is a 3-month-old dressed like a newborn?
For warmth, yes. Use the NHS rule of one more layer than you and adjust by the thermometer. What changes is safety around movement: stop swaddling when your baby looks like they are trying to roll, and check sleepsuits and sleeping bags still fit as they grow.
When should I stop swaddling?
The AAP advises stopping swaddling as soon as your baby looks like they are trying to roll over, whatever their age. Move to an arms-out sleeping bag with the right TOG for the room, and keep putting them down on their back for every sleep.
What TOG sleeping bag for a 3-month-old?
Pick the TOG by room temperature, not age. As a guide, about 2.5 TOG for 16–19°C, 1.0 TOG for 20–23°C and 0.5 TOG for 24–26°C, using your maker's chart. Check the back of your baby's neck after they settle and adjust the clothing underneath.
Does a 3-month-old need a hat outside?
On cold or windy days a soft hat helps, and in summer a wide-brimmed sun hat shades the face. Your baby is still under 6 months, so keep them out of direct sunlight too (NHS). Take any hat off as soon as you come indoors, and never use one for sleep.