Understanding Desert Locust population dynamics is a prerequisite for the implementation of a preventive management strategy against its invasions. The present study aims to describe these dynamics through conducting probability analyses of locust presence in time and space. Historical data from field surveys conducted by management teams in Mauritania and Morocco for the period 1988–2015 were used. Temporal smoothing and spatio-temporal extrapolations were performed on a monthly basis. We established monthly probability maps of locust observation following two scenarios: recession period (mainly solitarious phase) and invasion period (mainly gregarious phase). Also, observation probability maps of hoppers or mature adults allowed the identification of seasonal breeding areas. The methodology highlights the potentially favourable areas to be monitored every year. It also highlights the lack of information in some areas of the two countries. We observed that the seasonal survey process during recession periods follow the seasonal pattern of gregarious invasions. We argue that this is the result of climatic conditions related to the oscillation of the intertropical convergence zone. However, we advise that these similar yearly cycles should not hinder surveys in recession periods to be conducted in places not receiving swarms during invasion periods. Nevertheless, we conclude that these maps should be helpful for planning the preparation of survey teams in the field. This will reduce survey operation costs and decrease invasion risks.