The climatology of cold and heat waves in Brazil from 1961 to 2016

Extreme temperatures have caused various damages to society around the world. In Brazil, an example of that is the impact of cold and heat waves on public health. In order to analyse the temporal and spatial variability of such events, this study applied a single criterion to identify cold and heat waves. The study collected data on the events from daily temperature records from 264 weather stations over 56 years (1961–2016). The following parameters were used to describe each event: frequency, duration, severity, and intensity. The results showed that in all the Brazilian regions the frequency of heat waves increased and that of cold waves decreased between the years 1961 and 2016. The number of heat waves per year, notably, was greater than that of cold waves, and the mean duration of heat waves was about 1 day longer than that of cold waves. Additionally, it was found that cold waves were more severe and intense in areas often reached by cold air masses with temperatures below zero in most of Southern Brazil. In terms of severity and intensity of heat waves, two different configurations were observed: They were more severe in the Southern region and more intense in the Midwestern region of the country, and not so expressive in the Northern and Northeastern regions. Those findings justify the need for continuous updating of public policies focused on sectors often affected by cold and heat. The Southern region was the area of Brazil where most weather stations did not tend to increase heat wave frequency from 1961 to 2016. On the other hand, the other regions clearly showed a positive trend for heat wave frequency in most weather stations.