Victoria Falls is spectacular throughout the year but the best time to visit is from February to May - after the rainy season. This is when you'll see the greatest flow of water although it may be a little difficult to photograph the falls up close without getting your camera wet!
The lowest water levels occur at the end of the dry season - October and November - the time of year when temperatures remain uncomfortably hot throughout the day and night. Panoramic views of the falls are guaranteed but if you go on a Victoria Falls holiday during the late dry season, you may find that the Zambian side has dried up. If this is the case, be sure to view the ever-flowing Main Falls from Zimbabwe. Crossing the border between the two countries is a relatively quick and easy process.
However, late dry season is also peak safari season in Zimbabwe and neighbouring Botswana - the nearby Chobe River in particular offers sensational game viewing at this time of year - so you'll need to balance the two experiences in deciding when to go on a Victoria Falls safari holiday. As a compromise, we'd suggest visiting during the June - August period: you'll get great game viewing on your safari, warm days and cool nights, little to no rain, and plenty of water thundering over the falls.