The best time to visit Botswana depends on where you are travelling and what you are after. Peak season runs from July to the end of October, which is considered to be the optimum time for big wildlife viewing.
December to March is the hot rainy season, but excellent for general wildlife viewing in the Kalahari regions and birdwatching in the Okavango delta. Hotel rates are up to 30% cheaper at this time too.
June and November are considered shoulder season months, but provide excellent wildlife viewing conditions and are great times to visit. March is a good time to visit Nxai Pan, as it coincides with the zebra migration from the north.