Around here ......its necessary to use a sunblock if you are gonna be riding for much more than fifteen minutes.
A fair skinned gringo can get sunburned in about 10 to fifiteen minutes in that prime zone between 11:30 AM and 2:30 PM in June.
I am darkly tanned but I have to apply sunscreen to the nose and forehead or they will both crisp up nice after a day of riding.
It'll take a lot of tomatoes to ward off the sun around here.