Waterproofs get all the attention and they are only the outer shell. What a child wears underneath decides whether they are comfortable for two hours or counting down the minutes. Most children who come home miserable from forest school came home dry. They were cold, and they were cold because of the clothing choices made before the waterproofs went on.
This guide is about those layers: what each one is for, which fabrics work and which quietly sabotage the whole system, how clothing needs to fit for a child who climbs and crawls, and what a child will realistically agree to wear. It assumes the waterproofs are sorted; if they are not, our guide to forest school waterproofs covers the outer layer, and the full kit list covers everything that goes in the bag.
What's on this page
If you change one thing after reading this, change what your child wears next to their skin. It matters more than anything else on the list.
Dress for the worst twenty minutes
A forest school session is not one activity at one intensity. It is a child running about for a while, then sitting still for a story or a snack, then working on something with their hands, then running again. Body heat rises and falls sharply through that, and clothing has to cope with both ends.
The temptation is to dress for the average, which produces a child who is too warm while active and too cold while still. The better approach is to dress for the coldest, stillest twenty minutes of the session and give them a way to shed warmth for the rest.
That sounds like more clothing and it usually means differently arranged clothing: several thin layers rather than one thick one, with something that comes off easily and goes back on without help.
It also means sending them out slightly cool. A child dressed to feel comfortable standing in the playground at nine o'clock will be too warm within ten minutes of activity, and once they have sweated into their layers those layers will cool them for the rest of the session. Slightly cool at the start feels wrong to every parent and it is the right target.
The one exception is very young children, who generate less heat, move less consistently and are less able to tell you they are cold. For under-fives, err warmer and check on them.
What each layer is actually for
Three layers, three distinct jobs. Understanding which job each does makes the fabric choices obvious.
The base layer manages moisture. Its job is not warmth. It sits against the skin and moves sweat away from it, so the child does not end up with damp fabric against their body when they stop moving. A base layer that holds moisture is worse than no base layer at all, because it keeps drawing heat while it slowly dries.
The mid layer provides warmth. It does this by trapping air, which is what insulation is: the fibres themselves do very little, the still air between them does the work. That is why a thick loose fleece insulates better than a thin tight one, and why two thin layers usually beat one thick layer of the same total weight, since you get an extra pocket of trapped air between them.
The shell blocks rain and wind. It contributes no warmth of its own, but it does something important: it stops moving air stripping the warm air out of the mid layer. That is a real contribution and it is why a shell over a fleece feels dramatically warmer than a fleece alone on a windy day. It is a multiplier on insulation, not a source of it.
Once that is clear, the common failures explain themselves. A child in a shell and a thin t-shirt is cold because there is no insulation to multiply. A child in a thick coat with nothing underneath is cold once they sweat, because the moisture has nowhere to go. A child in cotton is cold whatever else they wear.
Note that a coated waterproof is not breathable, so moisture the base layer moves outward has limited escape. This is why sending a child out slightly cool matters so much: what does not get generated does not need to be dealt with.
Fabrics: what works and what sabotages
Cotton is the problem. It absorbs a great deal of moisture, holds it, and loses essentially all insulating value when damp. Worse, evaporation from wet cotton actively draws heat from the skin, so a damp cotton layer is not merely useless but harmful in cold conditions. A school polo shirt, cotton leggings or a cotton t-shirt under the waterproofs is the single most common cause of a cold child at forest school. This is not fussiness; it is the reason outdoor instructors have said "cotton kills" for decades, and while that phrase is aimed at mountain conditions, the mechanism is identical on a cold Wednesday in a wood.
Merino wool is the best base layer for this use. It keeps insulating when damp, resists odour, and regulates well across the active-then-still cycle that defines a session. It costs more and it is worth it if the budget stretches, particularly because children's base layers get handed down easily. Ordinary scratchy wool is a different matter, and a child who finds it uncomfortable will not wear it.
Synthetic base layers are the practical choice. Polyester and polypropylene move moisture well, dry fast and cost a fraction of merino. They hold odour more, which matters little for a two-hour session. Supermarket thermal tops are perfectly adequate here and there is no need to buy technical brands.
Fleece is the workhorse mid layer. Cheap, warm for its weight, dries quickly, and keeps insulating when damp. It is not windproof at all, which does not matter under a shell. A fleece from anywhere is a fleece.
Down is the wrong tool here. Excellent warmth for weight, and it collapses when wet and stops insulating almost entirely. Forest school involves damp. Use synthetic insulation or fleece instead.
One safety point worth knowing: many settings work with fire, and synthetic fabrics melt rather than char. If fire is part of the session, ask the leader what they prefer children to wear as an outer or mid layer. Wool behaves considerably better around sparks than fleece does.
Fit for a child who climbs
Forest school clothing has to allow a range of movement that ordinary school clothing never asks for: climbing, crawling, reaching overhead, squatting, dragging things.
Room at the shoulder and the seat. These are the two places clothing binds when a child climbs or crouches. A garment that is snug standing still becomes restrictive in a tree.
Sleeves that reach with arms forward. Check sleeve length with the arms extended in front, not hanging at the sides. Children reach constantly, and a sleeve that rides up exposes the wrist and lets water run in at exactly the point where cuffs are weakest.
Long enough in the body. A mid layer that rides up at the back when a child bends leaves a gap where cold air gets in. Longer-cut fleeces and base layers are noticeably better for this.
Nothing that dangles. Long scarves, loose cords and hanging toggles snag on branches and play equipment. Children's outdoor clothing sold in the UK is regulated on precisely this under BS EN 14682, which restricts cords and drawstrings, and the same logic applies to anything you add yourself. A neck gaiter is a better answer than a scarf.
Layers that move independently. Several close-fitting thin layers slide over each other; several bulky ones bunch and pull each other up when the child moves. This is another argument for thin over thick.
The test at home takes ten seconds: get them dressed as they will be, and ask them to reach up as high as they can and then squat right down. Anything that binds or gapes will do the same in the woods.
What forest school does to clothes
Worth setting expectations, because the damage is not mostly from rain.
Sap. Conifer and pine resin bonds to fabric and hardens. Deal with it the same day if you can. It is the most common permanent mark.
Fire pits. Sparks make small holes, and synthetic fabric melts into a hard bead rather than charring. One evening around a fire can finish a fleece.
Brambles and thorns. Snags and pulls, particularly on knitted fabrics. Woven and tightly knitted layers survive better than loose knits.
Mud and leaf mould. Mostly a washing problem rather than damage, though tannins from oak leaves and mud can stain permanently on light colours.
Knees. The commonest wear point on anything worn under waterproofs, because kneeling is constant.
Which is the argument for old clothes underneath, and for not sending anything a child is attached to. It is also an argument for dark or mid-tone colours rather than pale ones, purely on the basis of what stains show.
None of this means buying cheap and replacing constantly. It means putting the money into the outer shell and the boots, which do the protective work, and being relaxed about what goes underneath.
What a child will actually keep on
The best clothing system in the world fails if the child takes it off, and children are entirely willing to take things off.
Comfort is not negotiable. Itchy labels, scratchy wool, seams that rub, a collar that feels tight. Adults tolerate these and children do not. If a garment comes off repeatedly, assume there is a physical reason before assuming stubbornness. Some children are genuinely sensitive to particular fabrics and textures, and forcing the issue produces a child who resists the whole activity.
Let them choose where you can. Colour, pattern, which of two fleeces. A child who picked the garment wears it. This costs nothing and buys a surprising amount of cooperation.
Watch for the too-warm problem. A child who keeps stripping layers is often correctly telling you they are overheating. The answer is thinner layers they can adjust, not more layers or firmer instructions.
Hoods and hats compete. A bulky bobble hat stops a hood going up properly, so the child chooses one or the other. A thin beanie that fits under a hood avoids the conflict entirely.
Age matters. From around six or seven, appearance starts to weigh against comfort, and a child may prefer to be cold than to look wrong. Involving them in the choice earlier heads most of this off.
The practical upshot: kit that is comfortable and chosen gets worn for two hours. Kit that is technically superior and disliked gets taken off at the first opportunity and left on a log.
Dressing without help
At a setting, an adult is supervising a group rather than dressing one child. Anything your child cannot manage alone either does not get done or takes a leader away from everyone else.
The fastenings that cause trouble are predictable. Small zip pulls are difficult with cold wet hands, and a loop of cord or a fabric tab through the pull makes them manageable. Buttons on anything worn under waterproofs are worth avoiding entirely. Laced boots take a child several minutes and a leader considerably longer across a group, which is much of why wellies dominate.
Two practical habits help more than any gear choice. Practise at home before the first session, including getting waterproofs on over wellies, which is the step children most often get wrong. And mark the front of garments somewhere visible, since a plain fleece pulled from a bag in poor light gets put on backwards and then blamed for not fitting.
Independence is also why a one-piece suits a younger child at a well-staffed setting and a two-piece suits an older one managing alone. Coverage argues one way, independence the other, and the balance shifts as they grow. Our guide to one-piece versus two-piece works through where that line falls.
Three worked examples
What a typical primary-aged child might reasonably wear, assuming waterproofs and wellies over the top.
| Conditions | Base | Mid | In the bag |
|---|---|---|---|
| Mild autumn, 12–15°C, damp | Long-sleeved synthetic top | Thin fleece | Spare socks, sit mat |
| Cold winter, 0–5°C, wind | Merino or synthetic top and bottoms | Fleece, plus a second thin one | Thin hat, two pairs of gloves, thick wool socks, spare fleece |
| Warm summer, 18°C+ | Long-sleeved light top | None, carried only | Sun hat, water, light waterproof, long trousers already on |
Two notes on the summer row. Long sleeves and long trousers stay even in warm weather, because of nettles, brambles and ticks. And waterproofs still travel, because ground that looks dry at eleven o'clock was wet with dew at nine and a British afternoon changes quickly.
Adjust for the individual child rather than the thermometer. Some children run hot and some run cold, and after two or three sessions you will know which you have.
Frequently asked questions
What should my child wear under their waterproofs?
A non-cotton base layer next to the skin and a fleece over it. The base layer moves sweat away, the fleece traps warm air, and the waterproof stops wind and rain removing it. Add or remove mid layers according to the day rather than changing the base layer.
Why is cotton such a problem?
It absorbs a lot of moisture, holds it, and loses its insulating value when damp. Evaporation from wet cotton also draws heat from the skin, so a damp cotton layer actively cools a child. A school polo shirt under the waterproofs is the commonest reason children come home cold.
Is merino wool worth the money for children?
It is the best performer for this use, since it keeps insulating when damp and handles the active-then-still cycle well. Synthetic base layers do most of the same job for a fraction of the price. If budget is tight, buy synthetic and spend the difference on boots.
Can they wear school uniform underneath?
The trousers usually, the polo shirt ideally not, since it is almost always cotton. Many families send a synthetic long-sleeved top to change into, or wear one under the uniform on forest school days. Check whether the setting expects children to change at school.
How many layers is too many?
If they are stripping layers off within twenty minutes, that is too many. Children generate a lot of heat when active, and a child who overheats early spends the rest of the session in damp clothing. Send them slightly cool with a spare layer in the bag.
What about clothing near the fire?
Ask the leader. Synthetic fabrics melt rather than char, so many settings prefer wool or cotton outer layers around fire, which conflicts with the advice for the base layer. The usual answer is synthetic next to the skin and something less flammable over it, but the setting's own guidance takes precedence.
My child refuses to wear the layers. What now?
Check for a physical reason first: labels, seams, scratchy fabric and tight collars are common and children are more sensitive to them than adults. Then give them a genuine choice between two acceptable options. A garment a child picked gets worn; one imposed gets removed on the first log.
More from our resource library
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The outer layer: forest school waterproofs.
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Everything that goes in the bag: the forest school kit list.
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Younger children in a nursery setting: nursery and preschool waterproofs.
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The daily walk rather than the session: waterproofs for the school run.
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The wider category: the complete kids rainwear buyer's guide.
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Staying warm while stationary: what works when you are standing still.
Sorting the outer layer? Browse our children's all-in-one rainsuits, over-trousers, pack-away jackets and matched sets. Size charts, full specifications and care instructions are on each product page.
The Wet Weather Kids Editorial Team
We are a UK retailer specialising in unisex rainwear for families: pack-away jackets, waterproof over-trousers and all-in-one rainsuits for school runs, forest school and standing on wet touchlines. This guide is general buying advice. For the specification of any particular garment, see its product page.
