One of the couples from Australia wore these (not sure which brand) on our tour in Spain, when it was like 95 degrees. I am sure they were sun experts, given where they live, but they both looked totally red in the face and hot wearing those things in 95 degree heat. I never get burned, even though I am fair, from good use of sun block. One of the best strategies I have found is to put it on well before going out... up to an hour.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport