Heat and Kids in Thailand: The Hot Season, the Warning Levels, and What to Watch For

Most guides to the Thai hot season tell you to drink water and stay in the shade, which is true and not very useful.

What is more useful is knowing that Thai authorities publish a heat index with defined warning bands, that Bangkok has spent long stretches of recent years inside the dangerous one, and that the advice attached to each band is specific. Once you can read the number, the decisions get easier.

When the hot season actually is

Thailand's hot season runs roughly from March through May, peaking in April. Songkran in mid-April lands almost exactly at the hottest point of the year, which is not a coincidence.

It is worth being clear that this is not simply the warm end of a temperate summer. In 2026 Thai authorities warned that the national heat index could exceed 52°C, and Bangkok recorded a heat index of 51.9°C in late June, having already spent 18 consecutive days in the danger zone earlier in the year.

The heat index matters more than the air temperature because it combines heat with humidity, and humidity is what stops sweat evaporating. In Bangkok, a 36°C day can carry a heat index well above 45°C, which is why the thermometer reading on your phone consistently understates how dangerous the afternoon actually is.

The warning bands nobody tells you about

Thai authorities use four bands, and they are worth knowing because the official advice attached to each is concrete.

Watch, 27 to 32.9°C. Monitor heat alerts. Ordinary precautions.

Warning, 33 to 41.9°C. Reduce outdoor activity between 11am and 3pm.

Danger, 42 to 51.9°C. Monitor yourself and your children for symptoms actively. This is the band Bangkok sits in for much of the hot season.

Very dangerous, 52°C and above. Avoid outdoor activity altogether.

Why children are affected differently

Thai health authorities name young children among the groups needing particular attention during heat warnings, alongside the elderly, pregnant women, outdoor workers and people with existing health conditions. There are physiological reasons for that.

Children have a larger surface area relative to their body mass, so they absorb heat faster. They sweat less efficiently than adults. They take longer to acclimatise to a hot climate, which matters particularly for a family that has just arrived from somewhere cold. And crucially, young children do not reliably notice or report that they are overheating. They will keep playing.

That last point is the one to internalise. With an adult you can generally rely on them to stop. With a six year old on a playground in April, the adult is the thermostat.

Heat exhaustion, and the line it crosses

Heat illness is a progression rather than an event, and the useful skill is recognising the earlier stage, because that is the one you can fix yourself.

Heat exhaustion looks like heavy sweating, cool clammy skin, tiredness, dizziness, headache, nausea, muscle cramps, and a child who has gone quiet and floppy when they were fine twenty minutes ago. Irritability and unusual clinginess count too. This stage responds well to getting out of the heat, cooling down and drinking.

Heatstroke is a medical emergency and it is different in character, not just degree. The distinguishing features are a very high body temperature, skin that may have gone hot and dry because sweating has stopped, confusion, slurred or strange speech, unsteadiness, vomiting, seizures, or loss of consciousness.

The single most important distinction to hold onto: if a child who has been in the heat becomes confused, stops making sense, or stops sweating, that is not tiredness. Call 1669.

Do not spend time deciding whether it qualifies. Heatstroke damages organs quickly and the cost of an unnecessary call is nothing.

What to do, in order

For heat exhaustion, move the child out of the sun and into air conditioning or genuine shade. Remove excess clothing.

Cool them actively: cool water on the skin, a damp cloth at the neck, armpits and groin, a fan moving air across them. Cool rather than ice cold, since very cold water on a hot child can cause shivering that works against you.

Give fluids if they are alert and able to drink. Water is fine, and oral rehydration salts are better if you have them, which is a good argument for keeping sachets in the cupboard through the hot season. Do not give fluids to a child who is drowsy, confused or vomiting.

If they do not improve within a short time, or if any of the heatstroke signs appear, call 1669, Thailand's national emergency medical number. It is free, works from any phone, and English-speaking dispatch is usually available. If your family already uses a particular hospital, its own ambulance line is worth saving too, because a private ambulance will take you to that hospital rather than the nearest one.

School sport and the daily routine

International schools in Bangkok generally have hot-weather policies that move or cancel outdoor sport, and most handle this sensibly. It is still a reasonable question to ask, particularly if your child plays a sport that trains outdoors in the afternoon.

Ask what measurement the school actually uses and at what threshold activity changes. A school working from the heat index rather than the air temperature is using the better number.

For daily life, the practical shape of the hot season is that outdoor time moves to early morning and after about 5pm, and the middle of the day belongs indoors. That is why Bangkok's malls, indoor play centres and pools are as busy as they are in April, and leaning into that rather than fighting it makes the season much more pleasant.

Two habits worth building. Send children out with water rather than assuming they will find some, because they will not. And watch the first few weeks after arriving from a cold country particularly closely, since acclimatisation takes time and a newly arrived child is more vulnerable than one who has been here a year.