In their letter, Isaac I Bogoch and colleagues anticipated the international spread of Zika virus from Brazil through air traffic. Permissive climatic conditions for Aedes mosquitoes might have contributed to the explosive spread of Zika virus in Brazil. In fact, the 2015 El Niño caused exceptional climatic conditions in northeastern South America during winter and spring in the southern hemisphere. According to the US National Oceanic and Atmospheric Administration, the temperatures over north and eastern South America were “record warmest”, accompanied by a severe drought, throughout the second half of 2015.