Keeping a baby cool in summer is more urgent than many first-time parents realise. Babies cannot regulate their body temperature as efficiently as adults — they don’t sweat as effectively, they can’t tell you they’re too hot, and they overheat faster than older children. On a hot day, the difference between comfortable and dangerously overheated can happen in minutes in a hot car or a poorly ventilated room. Here’s everything you need to know to keep your baby safe and comfortable through the hottest months.
How Babies Overheat (and Why It Matters)
Newborns and young babies lose heat primarily through their head and have limited ability to sweat. Their thermoregulation system is immature, which means they rely heavily on their environment and their caregivers to keep them within a safe temperature range. Overheating is a risk factor for SIDS, and heat exhaustion in infants can escalate quickly to heat stroke.
The ideal room temperature for a baby is 16–20°C (61–68°F). In summer, maintaining this range indoors requires active management. Outdoors, sun protection and shade are the primary tools.
Signs Baby Is Too Hot
- Skin that feels hot and damp to the touch — check the back of the neck and the chest
- Flushed or red face
- Rapid breathing
- Increased fussiness or restlessness
- Sweaty hair or clothing around the neck
- Lethargy or unusual drowsiness (more serious sign)
A cool, dry neck is the best quick check. If the back of baby’s neck is sweaty, they’re too warm. Remove a layer and move to a cooler environment.
Keeping Baby Cool at Home
Room Temperature
- Keep curtains and blinds closed during the hottest part of the day (typically 11am–4pm). Closed blinds on south- and west-facing windows can reduce room temperature by several degrees.
- Cross-ventilate at night: When the outdoor temperature drops below indoor temperature in the evening, open windows on opposite sides of the house to create airflow. Close them again before the morning sun heats the outside air.
- Fans: A fan in the room helps but doesn’t cool the air — it moves it. For real cooling effect, place a bowl of ice in front of a fan. Point the fan away from baby directly; never aim it at a sleeping infant.
- Air conditioning: Effective, but maintain at least 18–20°C — an overcooled room is as problematic as an overheated one. Keep the aircon out of baby’s direct draft.
Sleep Environment in Summer
- Use a single lightweight cotton sheet instead of a sleep sack in very hot weather if the room is above 24°C
- For sleep sack guidance by room temperature, see our sleep sack TOG guide
- A damp cloth placed on baby’s forehead or a brief lukewarm bath before bedtime can lower body temperature enough to settle more easily
- Cotton, breathable bedding only — no synthetic fibres that trap heat
Dressing Baby for Summer Heat
The instinct to cover a baby up in summer is often counterproductive. The principles:
- Fewer layers, not more: In temperatures above 24°C, a single lightweight layer is usually enough indoors. Outdoors, a light layer actually provides sun protection more effectively than sunscreen alone on young skin.
- Natural fibres only: Cotton and linen breathe and wick moisture. Synthetic fabrics trap heat and moisture against the skin, creating discomfort and increasing heat rash risk.
- Loose and lightweight: Loose-fitting garments allow air circulation. Tight-fitting synthetics do not.
- Light colours: Light colours reflect heat; dark colours absorb it. White, pale pink, sage, and cream are better summer choices than navy or black.
- Sun protection through clothing: A lightweight long-sleeve top and hat provides more reliable sun protection than sunscreen for babies under 6 months, for whom sunscreen is not recommended. See our summer dressing guide for full outfit recommendations by age.
Keeping Baby Cool Outdoors
- Avoid peak sun hours: 11am–3pm. Plan outdoor time for morning and late afternoon when UV intensity and temperature are lower.
- Shade is non-negotiable under 6 months: Babies under 6 months should not be in direct sunlight. A pram canopy, umbrella, or tree shade are all appropriate. Pram covers that create an enclosed tent reduce airflow — check temperature inside and leave sides open.
- Never leave baby in a parked car: Car interiors reach dangerous temperatures within minutes even on mild days with windows cracked. This is a heat-related death risk, not a discomfort risk.
- Use a pram liner or carrycot with mesh sides for airflow. Solid fabric interiors trap heat.
- Water play: A shallow paddling pool with cool (not cold) water provides excellent temperature regulation and is usually enormously enjoyed from around 4–6 months. Supervise continuously. See our baby swimming guide for water safety rules.
Hydration in Summer
- Under 6 months (exclusive milk feeding): Breast milk and formula are sufficient hydration even in hot weather. Offer feeds more frequently in hot weather. Water is not needed or appropriate as an additional drink before 6 months.
- Over 6 months (on solids): Small sips of cool water between feeds are appropriate. High-water-content foods (cucumber, watermelon, soft fruit) also contribute to hydration. A baby who is well-hydrated will produce pale urine regularly — dark urine or very infrequent wet nappies suggests insufficient fluid intake.
When to Seek Medical Attention
Heat exhaustion in babies requires prompt action. Seek medical attention immediately if baby:
- Is unusually lethargic or unresponsive
- Has a rectal temperature above 38°C (100.4°F) and is also showing heat exposure symptoms
- Stops producing wet nappies (sign of dehydration)
- Has rapid or laboured breathing
- Has a sunken fontanelle (the soft spot on top of the head — indicates significant dehydration)
If you suspect heat stroke (temperature above 40°C, loss of consciousness, seizure), call emergency services immediately while beginning cooling: move to shade, remove clothing, apply cool damp cloths to armpits, groin, and neck.
For the complete summer outfit guide by age, see our summer dressing guide and our baby beach day guide.