The Lunar rainbow can only be experienced for 3 days a month during full moon at Victoria Falls. Take a night-time boat trip to view this for an hour or two with a guide after supper. What is a Lunar Rainbow? A full moon is bright enough to have its light reflected by raindrops, just as is the case for the sun making a rainbow, and although the moon’s light is not as strong as the sun’s, this is still worth a viewing if you happen to be at the Falls over the right dates. The best months for a Moonbow at Victoria Falls are: April, May, June and July, August.