The West Africa is one of the most vulnerable regions to climate change on our planet. This study specifically in Benin in Cotonou, aims to analyze the evolution of minimum and maximum temperatures recorded and homogenized for 1970 - 2008 obtained from the Agency for Safety and Air Navigation. Statistical techniques such as correlation analysis and statistical tests break detection and trend were used for analysis. The results reveal a polyphase increase, but significant in the average temperature during this period. The year 1986 appears as a date of rupture between two trends. Before 1986, the average temperature has dropped to 0.20 ° C per decade and increased in the same way between 1986 and 2008. The increase in average temperatures in Cotonou since 1987 is largely conditioned by the increase in maximum temperatures.