In Africa, it's not sunny every day (but it's sunny a LOT!) It can rain. Not usually for long, and only during certain times of the year...but it's possible. Don't let that scare you. "Rain Means Game" in the Serengeti. In fact, many people, myself included, prefer what they call the "rainy season". Which in reality is not really all that rainy. But it is green and the dust is down! The sky is big and wide over there and the cloud formations can amaze you. I personally love fog, mist and occasional rain. Everything seems more vibrant from those conditions in your photographs. Take a few kitchen trash bags and a rag with you to keep your gear dry. Some photographers toss a few of those silica packs you find in shoe boxes that absorb moisture in your bag. If the weather wants to play games with you for an hour or so, roll up the top of the vehicle and shoot out the windows. Besides... that low angle can be awesome. Some of my best pictures were in heavy heavy backlit dust or rain. Driving around becomes a little bit of a challenge but your guide can handle it. It'll make a great story, and isn't that what life is about? Remember, you came for adventure!