Botswana is an area that is overall nothing short of enormous.
About the same size as France, Botswana covers more than nine
latitudinal lines. There is a wide range of climate variation that
allows you to see and do it all in Botswana. Just about in the
geographic center of Africa, Botswana is situated on a plateau that is
about 1000 meters tall. This lowers the annual rainfall that Botswana
sees but does not stop it from having a climate range that is more
diverse than any you might see elsewhere.
There are seasonal changes in Botswana but it is not so great as the United States or Canada for example. The seasons are less distinct from each other. The annual rains begin in October or as late as November and may last through April. There may, even during the rainy season, be long spells where the area is quite dry.
The summer months coincide with the rainy months so from November to March there are many areas which are literally impassable. The mud may be thick and sticky and it is hard to reach many of the lodges. Some may even close for the season. This season does attract some incredible bird life and you'll see thousands of flamingos raising their chicks here during this time. Many of the animals are giving birth during the spring and summer months and the landscape is green and food is plentiful for the animals. If you're visiting during this time, be prepared for a few minor inconveniences as it may make travel difficult.
The rainy season is quite hot and moist as you might imagine, but early during April the rains begin to cease and the area is much drier and far more cool making the safari and the visits there much more comfortable. The rivers are lower during this time but they are flowing strong and the central areas will be much drier and the grass begins to brown.
This is also the best time for those who are considering a visit to Botswana to visit since the animals that you most want to see are going to spend a significant amount of time congregating around the watering holes, much like the movies that you've seen.
The greatest amounts of rain fall during December, January and February, but you should note that no matter what time of year it is in Botswana, the climate is literally amazing in that it is not normal that you will see rain more than two days in a row, making travel here at any time interesting and fun.