I have visited Kenya a few times, though always on the way to somewhere else. My experiences there are thus very limited, I have only visited Nairobi and its environs.
Its environs include a large, by European standards, National Park. Nairobi also has a snake park worth a visit to see a few local species of reptiles, and fish. But what Nairobi also contains is bushes with the occasional Chamaeleo jacksonii.
Nairobi is located in the highlands of the Rift Valley, which is why the British settled there - cool climate. Nights in winter get quite chilly, down to 10ºC the times I have been there. Normally the days warm up to the 20ºs, but quite often it is overcast. I have never been there during the middle of summer, but have seen days down to 15ºC and up to 30ºC. A quick check on the internet will give better ranges of temperatures. I have seen Chamaeleo jacksonii in large bushes in some of the parks. I find it best to go looking just as the morning sun is heating up the bushes. The chameleons are easier to see then. Some people use torches at night, but that is not advisable in most parts of Africa unless you know the place very well.
Poverty leads to high crime rates, and Nairobi is near the top. It is the only place I have been held up at gunpoint. Even during the day tricksters abound - they may try and talk to you, then a friend turns up and says he is with the security department and demand to see your money and credentials. You can not trust anyone you see, even the people working at the hotels, or the taxis outside.
The Nairobi snake park contains a nice variety of reptile and fish species. The reptile section is the oldest, and it shows. There are a few outside pit type cages housing Leopard Tortoises, White-throat Moniters, and snakes. But you have to look hard at all the bushes, as some of them contain Chamaeleo jacksonii.
There is a separate wall of glass-fronted concrete vivariums containing the venomous snakes. The new orchid section, and fish section are nicely done. Being new they have adapted modern design to display the fish and plants in an aesthetic way. The fish on display are species from the great lakes, Malawi, Victoria, and Tanganyika.
The Nairobi National Park is only a hours drive from the centre of town and contains most of the common antelopes, rhinos, and giraffes. The unfortunate thing is you can not get out of the tour bus, or car except at Hippo Pools. So looking for herps is difficult - I was not able to locate anything around Hippo Pools.
So if passing through Nairobi, a visit to the snake park is worth a stop over.