This chapter presents results from a 1-year field experiment in West Africa deploying a suite of ground-based instrumentation. Weather and climate over tropical West Africa are determined by the annual cycle of the West African monsoon. The relationships between the monsoon season and the displacements of the inter-tropical convergence zone and the inter-tropical discontinuity are briefly remarked, as well as the importance of atmospheric humidity in determining the strength of the monsoon. The scarce and discontinuous observations in the West Africa region cause lack of measurements with high temporal resolution and diurnal-to-annual coverage; conversely, long-term and continuous monitoring is essential for deepening the understanding of the mechanisms that are responsible for inter-annual variability of the West African monsoon. Within the African Monsoon Multidisciplinary Analysis project a wealth of observations from ground-based instrumentation, such as microwave radiometer, ceilometer, and microrain radar, were possible for a period of one year or more. The complete annual cycle of cloud cover, integrated water and liquid contents, and temperature profiles are reported. Furthermore, a distinct diurnal cycle, connected with the move of the inter-tropical discontinuity before the onset of the wet season, was observed and used to evaluate a mesoscale model.