A baby's skin is very thin and delicate, so despite your best precautions, a sunburn can happen. 
A sunburn is the result of overexposure to the sun's ultraviolet (UV) radiation. A baby's skin is very thin and delicate, so despite your best precautions, a sunburn can happen — and it may take only ten to 15 minutes of exposure to cause one. Your baby can even get burned on a cloudy or cool day because it's not the visible light or the heat from the sun that burns but the invisible UV radiation. Sunburns can be painful and can also cause more serious problems such as dehydration and fever.
You may not notice a sunburn immediately after you bring your baby in because the redness and pain of a mild first-degree burn can take several hours to appear. A more severe second-degree sunburn can cause red, tender, swollen, or blistered skin that's hot to the touch. It's extremely unlikely that a baby would get a third-degree burn — the worst kind — from sun exposure.
