The best time to see Mercury is just after sunset in late winter and early spring and before sunrise in late summer and early fall. Mercury is cited as the most difficult to see of the five bright planets
Three times a year, Mercury emerges into the evening dusk for a few weeks; at three other times during the year, it "ventures a little way into the morning sky," according to Space.com. Even at these times, however, it's not easy to see unless other conditions are just right. For instance, the planet needs to be nearly directly above the Sun, which most often happens just after sunset in late winter or early spring and before the sun rises in early fall or late summer.