Preschool-age children are more independent than toddlers and still a long way from regulating heat the way an older child does. They will keep playing through discomfort because the play is more interesting than the discomfort, they do not reliably stop to drink, and they will not connect feeling bad with being too hot.
Outdoor play is genuinely important and the answer is not to keep children inside all summer. The answer is to know what the actual heat load is, schedule around it, and check the playground itself, which is frequently the hazard rather than the air.
Outdoor time guidance by WBGT
No national standard exists for preschool programs specifically. These thresholds are conservative, derived from pediatric heat guidance. State licensing requirements take precedence where they exist.
| WBGT | Outdoor time | What changes |
|---|---|---|
| Under 82°F | Normal | Water available, shade available |
| 82 to 84.9°F | Normal, with prompts | Prompted water breaks every 20 minutes, encourage shaded play |
| 85 to 87.9°F | 45 minutes maximum | Shaded areas only, no running games, water every 15 minutes |
| 88 to 89.9°F | 20 minutes maximum | Full shade, quiet play only, or move indoors |
| 90°F and above | Indoors | Indoor gross motor activity instead |
Checking the playground
Surface temperature is the hazard most specific to this age group, and it does not track air temperature closely enough to guess.
- Test equipment with the back of your hand before children use it. If you cannot hold it comfortably for five seconds, it is too hot to touch.
- Check metal slides, climbing structures, handrails and any dark plastic. Metal slides in full sun are the most common source of playground contact burns.
- Check artificial turf and rubber safety surfacing, which can run 40 to 60°F above air temperature and radiate upward into every child on it.
- Check again later. A structure that was shaded at nine in the morning may be in full sun by eleven.
- Where equipment is reliably too hot, shade cloth is cheaper than the alternative and reduces surface temperature substantially.
Planning outdoor time around the heat
Go earlier
Move outdoor time into the early morning during hot weather. WBGT peaks later in the afternoon than air temperature does, so afternoon play is the worst option.
Follow the shade
Plan which part of the playground is in use by where the shade actually is at that hour, rather than by habit.
Prompt, do not wait
Build water breaks into the routine every 15 to 20 minutes. Preschoolers will not stop playing to drink on their own.
Dress for it
Light, loose, light-coloured clothing, a wide-brimmed hat, and sunscreen applied before going out and reapplied.
Signs a child is overheating
In this age group the early signs are behavioral. Staff should treat any of these as a reason to bring a child into shade and cool them:
A child who is confused, unusually sleepy, limp or has stopped sweating in the heat needs emergency care. Call 911, move them into shade or indoors, remove extra clothing and cool the skin with cool water while you wait. Do not wait to see whether they recover on their own.
What to tell families
- What your heat policy is, and at what point outdoor time is shortened or moved indoors.
- That you check playground surface temperatures, not just the air temperature.
- To send a wide-brimmed hat and light, loose clothing in hot weather.
- To send a labelled water bottle, and that staff prompt drinking rather than waiting for children to ask.
- To tell you if a child was unwell, had a fever recently, or slept badly, since all of those reduce heat tolerance.
Check the real number before outdoor time
Air temperature does not tell you how hard the heat is working on a child in full sun. The free app shows WBGT for your location and forecasts it hourly, so outdoor time can be scheduled rather than decided at the door.
- Real-time WBGT for your location
- Hourly forecast for planning the day
- The humidity, sun and wind behind the number
- Free on iPhone
WBGT is estimated from weather data with the peer-reviewed Liljegren model. Where a policy requires on-site measurement, use the app for planning and as a cross-check alongside your instrument.
Common questions
What temperature is too hot for preschool outdoor play?
Measured as WBGT, outdoor time should generally shorten from the mid 80s and move indoors above about 90°F. Air temperature alone is a poor guide, because humidity and direct sun change the actual heat load substantially.
How hot do playground slides get?
Metal slides and dark plastic equipment in full sun can exceed 150°F, which is hot enough to cause a contact burn in seconds. Always test with the back of your hand before children use the equipment.
How hot does artificial turf get on a playground?
Artificial turf and rubber safety surfacing commonly run 40 to 60°F above air temperature in full sun. They also radiate heat upward into children playing on them, which no air temperature reading reflects.
How often should preschoolers drink water outside?
Prompt water breaks every 15 to 20 minutes during outdoor play in hot weather. Children this age will not stop playing to drink on their own, and their thirst response lags behind their actual need.
What are the signs a preschooler is overheating?
Usually behavioral first: crankiness, withdrawal from play, clinginess, asking to be carried, complaining of a headache or stomach ache, flushed skin, or skin that has stopped sweating. Confusion or unusual sleepiness is an emergency.
Related WBGT guides
Know the real heat number
Real-time WBGT, flag levels and forecasts. Free on iPhone.
