Parents know the scene: their child charging around the garden in shorts at 14°C while they're standing in a jacket. Then the same child, tired and sitting still, complaining of cold at 18°C. The threshold isn't fixed — it depends entirely on what the child is doing.
Why children lose heat differently
Children have a higher ratio of body surface area to body weight than adults. That means they lose heat faster when inactive. When they're running and playing, they generate more heat per kilogram than adults and compensate easily. When they stop, heat loss overtakes production quickly.
The relevant variable is activity level, not age alone.
The moving child vs the still child
A child running at 15°C is probably fine in shorts. The same child sitting in a pushchair at 15°C will get cold faster than an adult sitting next to them would.
| Situation | Temperature | Advice |
|---|---|---|
| Active play, sunny | 15°C+ | Fine |
| Sitting still or watching | 18°C+ | Watch closely |
| Tired, end of day | 20°C+ | Long trousers likely needed |
Can you wear shorts today?
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Babies and toddlers
Very young children have less body mass and cannot move enough to generate compensatory heat. The general recommendation is to dress babies one layer warmer than an adult would be comfortable in. Shorts before 18°C for a baby is generally too cold.
Toddlers who are walking and moving fall between babies and older children — use the activity level as your guide.
The practical approach
Watch the child, not the thermometer. If they're running and sweating, shorts are fine. If they've stopped moving, look at their skin — if hands and legs are pale or mottled, they're getting cold regardless of what the app says.