Latitude.

Latitude is the angular distance of a point north or south of the equator.  The farther away from the equator the lower the temperature while the nearer to the equator, the higher the temperature.  Unlike areas near the poles, the mid-day sun is always high in the sky within the tropics and the sun rays at the equator concentrate their heating power onto a relatively small area  of the ground.
The ground surface near the equator therefore gets much hotter than that near the pole.   East Africa being a region that lies astride  the  equator  therefore  experiences  high temperatures, except for some areas of high altitude. The  effect  of  latitude  on  temperature  can  be illustrated as follows.