The continent of Africa is huge, covering over 11 million square miles, and is surrounded by oceans and seas. The resulting biodiversity is a product of that expanse, which includes one of the world's largest deserts, one of the world's largest rainforests, and 16,000 miles of coastline. That the climate would differ between the deep interior and the coastlines is not unexpected given that geographic diversity and the effects of ocean currents on the climate.
Coastal regions are distinct from interior regions of large landmasses all over the world. That is a product of the tremendous role ocean currents play in climate, and the further one moves from coastline to the interior of a large landmass, the less distinct the effects of those currents. With respect to the climate of Central Africa, the geography of that region is dominated by tropical rainforest, a product of the the region's proximity near the equator, which naturally produces warmer average temperatures, and of the heavy levels of rain fall. In short, the interior of Central Africa is very hot and very damp. The coastal areas are similarly hot, but tend to be considerably less humid, a direct result of the effects of the ocean currents on the climate, which produces a breezy and more open environment.
In addition to the natural phenomena that create distinct climates between the rain forests of the interior and the coastal regions, human interaction with the environment has resulted in changes to the regional climate. Deforestation of the interior combined with development of the coastal regions, where most of the human populations reside, has adversely affected the natural ecological balance of Central Africa. The major distinctions between interior and coasts, however, are a product of natural climatoligical patterns that keep all of Central Africa hot and lush with vegetation.