Warm days need light single layers: a short-sleeve bodysuit, light trousers, socks below 24°C, and a sun hat from 23°C, or from 20°C in sunshine.
For a baby of 6–12 months on a still, dry day:
24°C (75°F): short-sleeve bodysuit, pants and sun hat. Warm — light single layers. 23°C (73°F): short-sleeve bodysuit, pants, socks and sun hat. Warm — light single layers. 20–22°C (68–72°F): short-sleeve bodysuit, pants and socks. Warm — light single layers.
The NHS suggests a single lightweight cotton layer in hot weather. Babies under six months are best kept out of direct sun: shade first, and a wide-brim hat.
Toddlers are dressed a touch lighter, in a T-shirt and shorts, as the age table below shows.
Each piece comes on at its own temperature, a degree or two apart, so the outfit changes one piece at a time.
One light layer from 20°C, covered arms below.
Pants below 25°C (toddlers keep shorts to 21°C), lined ones below 13°C.
A sun hat from 23°C, or from 20°C in sunshine.
Socks below 24°C, warm ones below 12°C.
0–3 months, 22°C: short-sleeve bodysuit, pants and socks. 3–6 months, 22°C: short-sleeve bodysuit, pants and socks. 6–12 months, 22°C: short-sleeve bodysuit, pants and socks. 1–3 years, 22°C: T-shirt, shorts, socks and sun hat.
Still and dry: Warm — light single layers. Windy (feels like 19°C (66°F)): Short-sleeve bodysuit becomes long-sleeve bodysuit Raining (feels like 21°C (70°F)): No change Sunny (feels like 24°C (75°F)): Socks becomes sun hat In a carrier (your warmth counts on the body): No change In a car seat (no coat under the straps): No change
Check the neck — warm but not sweaty means just right.