As the smallest country on the African mainland, the West African country enjoys warm temperatures, which are cooler on its tourist-filled coast. The low-lying nature of the country, which runs along the Gambia River, also means there is little or no altitudinal variation. But there is a difference in temperature, and especially humidity, between the Atlantic coast in the west and places further upriver: inland sites are noticeably hotter and more humid, especially from March to June. Hence the vast majority of the holiday resorts are situated along the 50-mile coastline, where pleasantly warm winds also offer some relief from the heat.
SOURCE: THE GUARDIAN