Lady, EVOLVED 
does the temperature being higher actually increase the amount of UV radiation output by the sun or are people just conflating those two for some reason
@Lady idk about temperature but https://www.fda.gov/radiation-emitting-products/tanning/ultraviolet-uv-radiation#6 says that there's more in the summer: «The sun’s angle in relation to the Earth varies according to season. During the summer months the sun is in a more direct angle, resulting in a greater amount of UV radiation.»
(with https://www.epa.gov/sunsafety/sun-safety-monthly-average-uv-index seeming to confirm that point)
@alyssa i know there's more in the summer but europe has summer every year
my intuition is that it would be more important to tell europeans to wear sunscreen when they AREN'T in the middle of a heatwave because that's when they will be most likely to be outside at solar noon
@alyssa europe is evidently currently experiencing a heat wave so lots of people on masto are making posts with advice to people unused to the heat