Hotter, Longer and More Frequent Heatwaves: An Observational Study for the Brazilian City of Campinas, SP

Abstract Worldwide there is accumulated evidence of heatwave intensification due to climate change. Regional differences in the effects of heatwaves require local studies to implement public mitigation and adaptation strategies. This work analyzes and characterizes heatwaves’ occurrence for the city of Campinas, Brazil, through an observational study from 1956 to 2018. The definition of heatwaves adopted requires that the maximum and minimum daily temperatures be above the daily limits derived from climate normal 1961-1990. The annual and seasonal metrics of the number, frequency, and heatwaves’ duration showed significant and positive trends, except in winter. We found that the longest, the more intense, and the most frequent events occurred in the last 20 years and that a significant change in trend occurred at the beginning of the 1980s. Lastly, we performed an exploratory study of intra-urban variability, comparing heatwave metrics between two different weather stations that are 30 km apart in the city of Campinas. We found similar metrics patterns for the two weather stations, with more prolonged and more frequent heatwave events for the region's station with a higher rate of urban land occupation.