Of 5 trips over, I have seen only 1 snake depite countless hours in ground and elevated blinds. Remember that most Americans go over during our summer, which is their dry season and "winter". It can indeed get plenty cold in South Africa and Namibia in July.
That does not agree with snakes in general. I did have a single encounter with a snake. I am not inclined to kill snakes on sight, so that when a small one came slithering out of the long grass that was used to create the wall of the elevated blind that I was in, I took notice. It did not have the "typical" triangular head of a venomous snake so I watched it glide away back into the wall of grass never to be seen again. To this day I don't know if this was the right or wrong thing to do, as it was never addressed by the PH: just the other hunters who immediately said "did you kill it"?