What Should a 3–6 Month Old Wear to Bed at 20°C?

Where 20°C sits on the TOG scale

The 2.5 TOG band runs from 16°C to 20°C, so at 20°C you're at its warm end — the recommendation steps down to a 1.0 TOG sleeping bag once the room reaches 21°C. Unlike the cooler end of this band (16–17°C), where the main concern is whether the room might drift colder overnight, at 20°C the concern runs the other way: if the room warms past 20°C, the 2.5 TOG bag starts becoming too much. The bag is at the top of its range at 20°C, not in the cool middle.

For a 3–6 month old, the combination is a singlet under a long-sleeve bodysuit or pyjamas, with a 2.5 TOG sleeping bag. That's appropriate for a room that holds steadily at around 20°C overnight. If the room frequently reaches 21°C or above — common in early summer — dropping to the 1.0 TOG bag becomes the more accurate response rather than adjusting the layer underneath.

The rolling note applies at this age: by 4–5 months, many babies show rolling signs, and wrapping should already have stopped — at 3 months or at the first signs of rolling, whichever comes first. The fitted sleeping bag is the right call at this age.

Signs you've got it right (or wrong)

At 20°C, overheating is a more common concern than at 18–19°C — the room is at the warm end of the 2.5 TOG range, and any upward drift pushes toward 1.0 TOG territory. Check their back or tummy: warm but not damp is the goal. Damp hair around the hairline, flushed cheeks, or rapid breathing — particularly if you notice them later in the night when the room may have warmed — signal that the 2.5 TOG bag is running heavy.

If the touch check feels borderline, check the room thermometer at the same time. A room that reads 21°C or above is the culprit, not the layering itself. Adjust the bag on the next sleep rather than adding or removing base layers — the 1.0 TOG bag is designed for 21–23°C and is the cleaner solution than trying to compensate with a thinner layer under a 2.5 TOG bag.

Layering for 20°C in an Australian home

In concrete terms: a singlet under a long-sleeve cotton bodysuit or pyjamas, then a 2.5 TOG sleeping bag. The ergoPouch 2.5 TOG sleeping bag, or a Bonds cotton bodysuit paired with a Bubba Blue 2.5 TOG bag are standard options in Australian stores. Cotton and bamboo breathe better than polyester at the warm end of this temperature range.

Along the Wollongong and Illawarra coastline, autumn and spring evenings regularly sit at 18–21°C and hold steady overnight, moderated by the Tasman sea breeze that runs against the escarpment. A 20°C bedtime reading in Corrimal, Wollongong, or Figtree in April or September typically means a 19–21°C room by midnight — stable enough that the 2.5 TOG combination usually works through to morning without adjustment, with a check of their back or tummy on nights that reach 21°C and without the overnight-drop anxiety that applies in drier, more continental parts of the country.

When room temperature shifts overnight

Coastal stability has a seasonal limit. In October and November, as summer approaches on the NSW south coast, a 20°C Wollongong bedroom at bedtime can warm toward 22–23°C by midnight as the day's heat builds in the house before the overnight sea breeze strengthens. From 21°C the 1.0 TOG recommendation applies, and by 22°C the 2.5 TOG bag is running noticeably heavy.

Checking the room thermometer at the first night feed in October and November confirms what the season is doing to overnight temperatures. If the room has settled at 21°C or above, switching to a 1.0 TOG bag for the following night is the right call. The transition is clean: keep the long-sleeve bodysuit, leave off the singlet, and use the lighter bag. You don't need to rethink the whole layering system.

Frequently asked questions

Try a different temperature or age

• What a 3–6 month old should wear at 19°C
• What room temperature is best for baby sleep in Australia?
• TOG rating chart: which TOG for which room temperature