Can you get sunburned after 5pm?

Yes. The closer you are to noon the stronger the sun's rays hitting the earth, so before 10am and after 2pm are safer, but not entirely safe. I try to be inside or in the shade in June, July and August between 10am and about 5pm but I've definitely gotten slight sun burns biking after 5. Remember that at the peak of summer the sun doesn't set until after 9pm, so it can still be pretty high in the sky at 5.