Ghana is located very close to the equator, which gives it two main seasons that is the rainy and dry. But during the dry season it is still very humid. Ghana has a short series in season called the harmattan. Its usually very windy and dry. 

like that of the rest of the Guinea Coast of west Africa, is determined largely by the interplay of two air masses: a hot, dry continental air mass that forms over the Sahara and a warm, humid maritime tropical air mass that forms over the South Atlantic.

Both air masses move toward the equator with their hemispheric winds and meet at the Guinea Coast for several months each year. Continental air moves southward with the northeast trade winds, known in western Africa as the harmattan.

The maritime tropical air moves northward with the southwest trades. The zone where these air masses converge is characterized by seasonal line squall precipitation.

The convergence zone itself oscillates north and south, following the seasonal movements of the overhead sun and the thermal equator.

In August it reaches its most northerly position in the central Sahara with latitude of 21° about to the north pole.

In January the position change to its most southerly position about 7° N which is  a few miles from the north of the Ghana coastline.

Rains occur when the dominant air mass is maritime tropical, and drought prevails when continental air and the harmattan dominate.