What this is about
At the front door, you judge the sun by how it feels. A cool breeze or a hazy sky makes it seem gentle, and that is how babies get sunburned in April. The part of sunlight that burns skin can't be seen or felt. The UV index is the forecast's number for it, from 0 upward, and it has nothing to do with heat.
Below 3, a baby needs no sun protection. From 3, the canopy or a parasol, a sun hat and light clothes over the arms and legs keep the sun off. The number your weather app shows for the day is only its peak, though. Most of the day sits below it, so what you want to know before a walk is which hours reach 3.
What UV index is safe for a baby?
There is no separate scale for babies: 3 is the line at every age. A baby's skin is thinner than yours, though, so it burns sooner at the same number, and the higher the number, the faster. Under 6 months the protection is shade and clothes alone, and sunscreen joins at 6 months.
UV 0–2
LowNo sun protection is needed, even for fair skin. Go out whenever it suits you.
UV 3–5
ModerateThis is where it starts. The canopy out or a parasol up, a sun hat on, and light sleeves and pants over the arms and legs. The walk goes ahead as planned.
UV 6–7
HighFair skin burns quickly. Keep to the shady side of the path, and sit in the shade rather than on the open lawn.
UV 8–10
Very highKeep the time in open sun short, and take the walk before or after the peak. Pick shade that casts a dark shadow: the dappled shade of a thin tree lets too much sun through.
UV 11 and higher
ExtremeReached in midsummer nearer the equator and high in the mountains. Walk in the early morning or the evening, and spend the middle of the day indoors or in deep shade.
Which hours need the hat?
Most weather apps splash one dramatic number across the screen: UV 8. That sounds intimidating, but the peak holds for an hour or two in the early afternoon. It does not mean you have to hide inside all day.
What shapes your day is the window of hours at 3 or more. Scroll the hourly forecast, find the first hour at 3, then the last one. Those hours are when the hat, the canopy and the sleeves matter, and a walk before or after them needs none of it.
The UV on a clear day in Chicago, hour by hour.
The UV over a clear day
June: the sun at its highest
09:00–17:00hat and shade
The UV peaks at 8 around 13:00. Before 09:00 and after 17:00, a walk needs no hat.
April: the same hours as June
09:00–17:00hat and shade
The air may still call for a cardigan, yet the peak is only one step lower than in June. The first sunny spring days are when the hat comes back out.
October: a few hours around lunch
10:00–15:00hat and shade
The sun stays lower, so the window shrinks and the peak stops at 5. In winter, most days never reach 3 at all.
The peak sits later than you would guess. With daylight saving time the sun is highest around 13:00, not at noon, so 16:00 is about as strong as 10:00. On a hot day the early hours are the coolest too, so the morning before the window opens is often the best time for a walk.
The shadow check: can you tell without your phone?
Roughly, yes. Your shadow shows how high the sun is, and the higher the sun, the stronger the UV. Over a summer day it shrinks toward lunchtime and grows again in the afternoon, the same way the hourly numbers rise and fall.
The shadow check
Good: Longer than you: the sun is still weak
The sun sits low, and its UV with it. An ordinary walk, with the hat in the basket for later.
Not good: Shorter than you: hat and shade
The sun stands high, and so does the UV. Hat on, canopy out, and keep to the shady side of the path.
Good: Longer again: the strong hours are over
The sun has dropped and the UV with it, even when the afternoon is the hottest part of the day. The hat can come off.
You don't need to stand up for it. On the picnic blanket, a bottle or a toy works the same way: compare its shadow with its height.
Good: Much longer than the toy
The sun is low and the UV weak. A shadow only a little longer can still mean UV 3 at midday in the fall.
Not good: Shorter than the toy
The UV is high, whatever the season or the temperature.
A cool spring day can burn, a hot evening cannot
The UV index follows the height of the sun, not the temperature. The midday sun stands as high in late May as in mid-July, so a cool, breezy day in May can bring the same UV as a hot one in July. That is why a knit cardigan and a wide-brim sun hat can belong on the same baby: the cardigan for the chill, the hat for the UV you can't feel.
The reverse happens every summer evening. At 19:00 the air might still be 28°C (82°F) and the asphalt warm under your shoes, but the UV index has dropped to 1. Your baby can stay in a single light romper, and the sun hat can come off while the canopy stays up against the glare.
Snow, sand, water and mountains push the number up
The forecast is for ordinary ground. Bright surfaces throw the sun back up and add to it, and that bounced light reaches your baby from below, under the canopy and under the beach umbrella. Height adds to it too, and so does a holiday further south, where the sun climbs higher and the numbers run above what you know from home.
Up to 25% moreAt the beach
Dry sand throws back about 15% of the UV and sea foam about 25%. It comes in under the umbrella from below, so at the beach the hat and the sleeves stay on even in the shade.
Up to 80% moreOn fresh snow
Fresh snow throws back up to 80% of the UV and nearly doubles the dose. A bright day on snow counts as a sunny one for the skin, however cold it is.
10% more per 1,000 mIn the mountains
Higher up there is less air to stop the UV, about 10% more for every 1,000 meters (3,300 feet). The mountain forecast runs higher than the valley's on the same day.
Questions parents ask
Is UV 1 or 2 safe for a baby?
Yes. At that level a few minutes of direct sun do no harm, even to fair baby skin, and the hat is only for the glare. The canopy can still stay up on a warm day, because it keeps the seat cooler.
Is UV 3 bad for a baby? And UV 5?
3 is where protection starts, and it is no reason to cancel the walk. At 3 or more, a quarter of an hour of open sun is enough to start damaging bare skin, sooner on a baby's thinner skin, so the hat and the shade go on from the start. At 5 the protection is the same as at 3, with less margin for a forgotten hat.
At what UV index do babies need sunscreen?
From 6 months, at UV 3 or more, on what the hat and the clothes leave bare: the face, the ears, the backs of the hands and the tops of the feet. Before that, shade comes first, and a little sunscreen on the face only when there is no shade to be had.
Can I take my 2-month-old out in the sun?
Out, yes. Into the sun, not for long. Until 6 months, a baby stays in the shade of the canopy or a parasol, because a young baby overheats quickly in direct sun, and from UV 3 the skin burns too.
Is there UV on a cloudy day?
Yes. Up to 80% of the UV comes through cloud, and thin haze changes it hardly at all. The forecast number already allows for the clouds expected that day, so a cloudy day with a 4 in the forecast is a 4. Only a thick, dark overcast brings the index right down, and the forecast shows that too.
Can a baby get sunburned through a car window?
Not a red burn on a normal drive, because car glass stops most of the rays that burn. The windshield is laminated and holds back some of the UVA as well, but the side and back windows let most of it through, and UVA damages skin without a visible burn. On a long sunny drive, a mesh shade on the window beside the seat fixes it.
Is there a UV index too high to take a baby outside?
No. A high number shortens the walk and moves it to the morning or the evening, but it never rules it out. On an ordinary summer day, a shaded path with the hat on is fine.
Does the UV index change for toddlers and older kids?
The number means the same, and 3 stays the line. What changes is the child. A toddler walks out of the shade you parked the stroller in, so from about a year the sun hat, a shirt and sunscreen do the work the canopy used to do, and the hours of the window still say when.
If the skin becomes sunburned
Move your baby out of the sun and apply cool, damp compresses to soothe the skin. Call your pediatrician for guidance. Seek urgent medical care if you see blistering, fever, chills or if your baby seems lethargic.
