On: The UV index is not the warm sensation of sunlight on bare skin

[koolba]

Overcast days are the worst offenders for sunburn because the melanin impaired don’t feel the heat of the sun to remind them they are going to roast.

[cortesoft → koolba]

I have always heard sunny snow days are the worst, because you feel cold, but the sun is still hitting you, plus reflecting off the snow to hit you twice.

[nephihaha → cortesoft]

You can get sunburn from light reflecting off water as well, in hot places. Maybe not on its own, but certainly in conjunction with direct sunlight.

[bwnkl → koolba]

I agree that it very much depends on latitude and time of year. In most of Europe, overcast days usually don't present much of a problem for me, but I remember spending a day at the beach in Ecuador under very dense cloud cover and getting one of the worst burns I've ever had

[pazimzadeh → koolba]

They are also the worst because you get mostly UVA since UVB has a harder time penetrating through cloud cover

[nephihaha → koolba]

Depends which part of the world you are in. I've never been sunburnt on an overcast day where I live.

[saltcured → nephihaha]

One of my worst sunburns was in San Diego on an extremely gray day. I should have known better.

The right thickness marine layer can make the sky seem dim but it's like one massive UV diffuser from horizon to horizon.