The city of Manaus (Brazil) is located in the central part of the largest tropical forest in the world, the Amazon rainforest, and has a population of approximately 2 million inhabitants. Osmar Pinto Jr., Iara Regina Cardoso de Almeida Pinto, and Osmar P. Neto showed that the lightning activity in Manaus is larger than that in the regions around the city and it has been increasing in the last four decades with the increasing of the urban area of the city. These results suggest that these spatial and time variations are related to the Urban Heat Island effect, since it is believed that the Urban Heat Island effect influences thunderstorm formation and evolution and, in consequence, the lightning activity. Therefore, they suggest that the replacement of the forest by urban areas tends to increase the lightning activity in the Amazon region. These results were published in American Journal of Climate Change in December 2013 .