Why Summer UV Peaks at Solar Noon
The riskiest hours of the day, and how to plan around them.
Up to 80% of UV rays pass through clouds on overcast days.
Photokeratitis — 'snow blindness' — is essentially a sunburn of the eye's surface.
Frequently asked questions
Does snow increase UV exposure?
Significantly. Fresh snow reflects up to 80% of UV rays, effectively hitting your skin twice — from the sky and from the ground. Combined with altitude on the slopes, this makes winter sun protection of the face, ears, lips and eyes essential.
Is sunscreen necessary on cloudy days?
Yes. Up to 80% of UV rays pass through clouds, and UVA — the deeper-penetrating, aging wavelength — stays fairly constant regardless of cloud cover. A cool, overcast day can still deliver enough UV to damage skin, so daily broad-spectrum sunscreen is recommended.
Does UV get stronger at higher altitude?
Yes. UV intensity increases roughly 4–5% for every 1,000 feet (about 300 m) of elevation, because there's less atmosphere to filter it. At a mountain resort UV exposure can be substantially higher than at sea level — a key reason sunburn is common while hiking or skiing.
r/30PlusSkinCare: 'Is winter sun damage actually a real thing?'
Sources & citations
- American Academy of Ophthalmology, photokeratitis (snow blindness) guidance
- aao.org ↗