Not sure why you mention sunscreen. It’s not like the sun shines brighter during a heatwave! And it’s not like sunscreen keeps you cooler. (OK, I guess technically the mineral sunscreens, the ones that make your skin look ghostly white, would increase your skin albedo / reduce sun absorption, exactly to the extent that they make your skin looks ghostly white. But better to just wear a white hat instead!)
My understanding is that UV exposure is determined mainly by solar angle from zenith (which in turn depends on days-from-summer-solstice and hours-from-solar-noon), whether the sky is clear vs cloudy, ground elevation, how much stratospheric ozone happens to be overhead today, and whether you’re in direct sunlight (and/or have lots of line-of-sight to the blue sky). I don’t think any of these things would be different from usual during a heat wave.
If you are in a building where the thermodynamics are bad, (cooler outside than inside) then you might be spending lots of time outside. A heatwave is correlated with lack of cloud cover.
Not sure why you mention sunscreen. It’s not like the sun shines brighter during a heatwave! And it’s not like sunscreen keeps you cooler. (OK, I guess technically the mineral sunscreens, the ones that make your skin look ghostly white, would increase your skin albedo / reduce sun absorption, exactly to the extent that they make your skin looks ghostly white. But better to just wear a white hat instead!)
My understanding is that UV exposure is determined mainly by solar angle from zenith (which in turn depends on days-from-summer-solstice and hours-from-solar-noon), whether the sky is clear vs cloudy, ground elevation, how much stratospheric ozone happens to be overhead today, and whether you’re in direct sunlight (and/or have lots of line-of-sight to the blue sky). I don’t think any of these things would be different from usual during a heat wave.
If you are in a building where the thermodynamics are bad, (cooler outside than inside) then you might be spending lots of time outside. A heatwave is correlated with lack of cloud cover.