There is a night every spring when it happens. You zip your baby into the same cosy sleeping bag that got you both through winter, settle them in the cot, and a couple of hours later you find a pink, damp-haired little person who has clearly been too warm for a while.
Nobody hands you a manual for the change of seasons. Daylight saving starts on the first Sunday in October, the evenings stretch out, and the questions get trickier. What should a baby wear to bed on a muggy night? Does the fan stay on? What do all those numbers on the sleeping bag labels actually mean?
Here is a calm, practical way through the warm months, from the cot to the pram.
Why warm nights catch parents out
Babies are not good at managing their own temperature. They heat up faster than adults, they do not sweat as much, and they mainly control their temperature through the head and face. An adult who gets too hot kicks off the sheet. A small baby cannot, so whatever we put them in is what they sleep in.
Overheating is a known risk factor for sudden unexpected death in infancy, which is why safe sleep advice takes it so seriously. The good news is that getting it right takes a few simple habits and a hand on your baby’s tummy, not gadgets.
Sydney adds its own twist. At Sydney Airport, the average overnight low climbs from about 13.5 degrees in October to 19 degrees in January, and the average number of days reaching 30 degrees more than doubles over the same stretch.
Then there is the southerly buster. These sudden changes charge up the coast mostly between October and February, and Sydney gets about five a year. The stronger ones tend to arrive in the late afternoon or early evening after a run of hot days, and the temperature can fall 10 to 15 degrees in under an hour.
Start with the room, not the label
The simplest rule is also the most useful one: dress your baby the way you would dress yourself to feel comfortable in that room. If you would be happy in a light singlet and a sheet, your baby does not need a long-sleeved suit and a thick sleeping bag.
There is no single right room temperature for a baby’s sleep, and no evidence that holding a room at a set number prevents sudden infant death. A thermometer can help you pick a sleeping bag, but it is not essential. Your baby’s body will tell you far more than the wall will.
Daylight saving also changes the picture. Once the clocks go forward, bedtime arrives with an extra hour of evening light, often after the afternoon sun has been warming the house, so a bedroom that felt fine in August can feel warmer at bedtime in October. Closing the curtains and blinds against the afternoon sun, then opening the windows once it cools outside, can take the edge off before you even get to the clothes.
Making sense of TOG ratings
If you use a sleeping bag, the label will carry a TOG number. TOG is short for Thermal Overall Grade, and it measures how much warmth the fabric provides. In Australia, ratings run from 0.2 TOG, the lightest, up to 3.5 TOG, the warmest.
TOG describes the bag, not the room, so the trick is to match the two. Most brands print a guide on the packaging that pairs each rating with a range of room temperatures, and that guide is the best starting point for the bag you own. A bag that suited a July night is likely to be too warm in December, so a low TOG bag for the warmer months is worth having.
If the numbers on the label are a mystery, this plain-English guide to TOG ratings explains what each level is for and what tends to go underneath it.
What goes underneath
The sleeping bag or wrap is the outer layer, so it does most of the work. Underneath, keep it light, ideally in natural fabrics such as cotton or bamboo.
On a warm night. A nappy and a singlet, or a sleeveless and legless bodysuit, is often plenty under a light bag. On a hot night, a nappy alone under a low TOG bag can be enough.
If you wrap. Use only a lightweight cotton or muslin wrap, never a bunny rug or blanket, and keep it to a nappy and singlet underneath in warm weather. Wrap from below the neck so the face stays clear. Stop wrapping once your baby shows signs of rolling or reaches three months, whichever comes first, and never put a wrapped baby into a sleeping bag.
Skip the extras. A well-fitted sleeping bag replaces bedding, so there is no need for a blanket on top. Leave hats, beanies and headbands off for sleep, choose a bag with no hood, and check that the neck is fitted and the armholes are the right size so the bag cannot slip up over your baby’s face. Put your baby down on their back, with their feet at the bottom of the cot and their head and face uncovered.
The tummy test
Hands and feet are not a reliable guide. They often feel cool even when the rest of your baby is perfectly warm, which is normal, and it is tempting to add a layer that is not needed.
Instead, slide a hand onto your baby’s tummy or back. Warm is what you want. Hot and clammy skin, flushed cheeks or sweating mean your baby is already too warm, so a layer needs to come off. A cool tummy can mean they need another layer.
On hot nights, check on your baby regularly, including when you go to bed yourself. If your baby has become too warm, remove a layer and offer a feed. Babies under six months may want extra feeds in hot weather. Breast milk covers a breastfed baby’s needs, so extra water is not necessary, while a bottle-fed baby may need more bottles than usual.
Fans, air conditioning and the southerly change
A fan helps in a stuffy room. Choose one that turns from side to side, keep it out of your baby’s reach, and point it so it moves the air around the room rather than blowing straight at your baby.
You do not need to leave the air conditioning on all night. If you do use it, dress your baby for the room it creates, not for the forecast outside. A baby in a cool, air-conditioned bedroom may need a slightly warmer bag than the weather suggests.
When a southerly is forecast, you may put your baby down on a hot evening and find the air outside much cooler an hour later. Keep the next layer up within easy reach and do a tummy check before you go to bed. A bodysuit folded beside the cot is much easier to find in the dark than the right drawer.
Naps on the move
Plenty of Eastern Suburbs babies drift off in the pram, on a lap of Centennial Park or a stroll along the beachfront. As the weather warms, one habit matters most: never drape a wrap, muslin or blanket over the pram to block the sun. Even light fabric reduces airflow and traps heat around your baby, and it makes it harder to see how they are going.
Use the pram’s own hood, an umbrella or natural shade instead. In Centennial Park, Paperbark Grove, the double avenue of paperbarks near the Paddington Gates, is a shady spot on a bright morning. Plan walks for the cooler early morning rather than the hottest part of the day, which is usually midday to early afternoon, and check on your baby often.
A pram is not a substitute for a cot. If your baby falls asleep on the walk, move them to their cot once you are home, and never leave them unattended in the pram. On a hot day, do not leave them to sleep in it. The same care applies in the car: never leave your baby alone in a parked car, and never cover the capsule with a rug or towel to shade it.
When to call for help
Babies can overheat and dehydrate quickly. Fewer wet nappies, darker urine or a dry mouth are early signs worth a call to your GP or child and family health nurse. If your baby is drowsy or floppy, pale or cold, has sunken eyes, refuses to drink or looks unwell, call triple zero (000) and ask for an ambulance.
If your baby simply does not seem right to you, trust that feeling and get them checked.
The short version
Dress your baby the way you would dress yourself for the room. Keep the outer layer light, keep the head and face uncovered, never cover the pram, and let the tummy test have the final say. Within a couple of warm weeks it becomes second nature, and you can get back to enjoying those long Sydney evenings.
