The weather in Kenya is always hot and sunny, but May is the height of the rainy season. This means there are less tourists and some parks are only accessible with a 4WD.
As a rule of thumb, you can see the animals in the parks more easily outside the rainy season, because they come out of the bush more to find water.
It's what you prefer. I personally think rainy seasons in tropical countries have a very special atmosphere. It would not hold me back from visiting Kenya. But to everyone his one.
