17 August 2026 · Veronica Chi
Business & Product Director · Mum of two
Keeping Babies Cool During the Summer
Babies heat up faster than adults and shed heat less efficiently. They sweat less effectively, they have more surface area relative to their mass, and they cannot remove a layer, move to the shade or ask for a drink. In hot weather that combination makes the adult in the room the entire cooling system.
Dressing for heat
- One light layer is usually enough indoors — a short-sleeved bodysuit, or just a nappy in genuinely hot conditions.
- Natural, loose and breathable. Bamboo and cotton move moisture away from the skin; synthetics trap it against the skin, which is what turns warm into prickly.
- Loose beats tight. Air moving across skin is how heat leaves.
- Check the back of the neck rather than the hands. Damp hair and a sweaty back mean too warm.
- Change them if they are damp. Sitting in a wet layer causes heat rash quickly.
Sleep in hot weather
The safer-sleep rules hold: on the back, firm flat surface, clear cot. Heat changes what goes on the baby, not where or how they sleep.
- A sleep sack in the lightest weight, or just a nappy and vest above roughly 27°C. Adjust the layer, not the practice.
- Never cover the cot or pram with a blanket to make it dark — airflow stops and the temperature underneath rises fast.
- Fans help by moving air; point them at a wall rather than at the baby.
- With air conditioning, remember that a room dressed for at 8pm is not the room at 2am when the unit has cycled off. Check on a night waking.
- Cool the room before bedtime rather than during, and keep curtains closed through the hottest part of the day.
- A cool bath before bed helps — tepid rather than cold. Cold water causes shivering, which generates heat.
Fluids
- Under six months, breastfed babies do not need water — they need more frequent feeds. Breast milk adjusts, and the early part of a feed is more watery.
- Formula-fed babies under six months can be offered small amounts of cooled boiled water between feeds in hot weather.
- Over six months, offer water in an open or straw cup with meals and between them.
- Watch nappies. Fewer wet nappies than usual is the earliest reliable sign of dehydration.
Sun
- Under six months: keep out of direct sunlight entirely. Shade, clothing and a wide-brimmed hat — not sunscreen, whose use on very young skin is not generally advised.
- From six months: sunscreen of at least SPF 30 with good UVA protection, alongside shade and clothing rather than instead of them.
- Reapply every two hours and after any water or sweating.
- Avoid direct sun between about 11am and 3pm.
- A pram parasol or a properly ventilated sunshade — never a muslin over the hood, which traps heat.
- Sunglasses with UV protection are worth it for older babies. Ultraviolet exposure to the eyes accumulates.
The car
Never leave a baby alone in a parked car, for any length of time, with any window arrangement. Interior temperature rises far faster than most people expect and heatstroke can follow within minutes. Before a journey, cool the car down first, use window shades, and check the buckle and the seat surface with your hand — dark plastic and metal fittings get hot enough to burn.
Heat rash, briefly
Small red or clear bumps where sweat has been trapped — in skin folds, under the chin, at the nappy line. It is common, it is not dangerous, and it clears when the baby cools down. Loose clothing, a tepid bath, and leaving the area open to the air are the whole treatment. Creams generally make it worse by blocking the ducts further.
Signs of heat illness
Get medical help urgently if you see any of these.
- Hot skin with no sweating.
- A temperature of 38°C or above in a baby under three months, at any time.
- Unusual drowsiness, floppiness or difficulty waking.
- Very few wet nappies, a dry mouth, no tears when crying, or a sunken fontanelle.
- Rapid breathing or a racing heartbeat.
- Vomiting, or refusing to feed.
- Skin that is pale, clammy or mottled.
While waiting for help: move to the coolest place available, remove clothing, cool the skin with tepid water, and offer fluids if the baby is alert enough to take them.
Questions parents ask
What should a baby wear to sleep in hot weather?
The lightest sleep sack available, or a nappy and vest above roughly 27°C. Adjust the layer rather than the practice — on the back, firm flat surface, clear cot. Check the back of the neck rather than hands and feet.
Can babies under six months drink water in hot weather?
Breastfed babies do not need water — offer more frequent feeds instead, since breast milk adjusts and the early part of a feed is more watery. Formula-fed babies under six months can have small amounts of cooled boiled water between feeds.
Can I put sunscreen on a baby under six months?
Sunscreen is not generally advised for babies under six months. Keep them out of direct sun entirely and rely on shade, loose clothing and a wide-brimmed hat. From six months, use SPF 30 or higher alongside shade rather than instead of it.
Is it safe to cover a pram with a muslin to keep the sun off?
No. Covering a pram traps heat and stops airflow, and the temperature underneath rises quickly. Use a properly ventilated sunshade or a parasol that leaves the airflow intact.
Sources
- NHS — Heat exhaustion and heatstroke
- NHS — Sunscreen and sun safety
- The Lullaby Trust — Safer sleep advice
This guide is general information, written to help you understand a topic and ask better questions — it is not medical advice and does not replace your own doctor, midwife or paediatrician. Anything that worries you about your baby belongs with them.