Influence of climate and heatwaves on dengue transmission in Sao Paulo and Natal, Brazil

PLOS One | https://doi.org/10.1371/journal.pone.0334838 October 24, 2025 6 / 13 temperatures were constant, with small variations and generally warm temperatures, typical of a tropical climate (Fig 3). The temperature range in Natal was smaller than in Sao Paulo, averaging 7.4 °C, which is expected due to the city’s prox- imity to the sea and to the Equator, moderating daily temperature variations. Dengue infection peaks in Natal are more regular and recurrent than in São Paulo, with outbreaks typically occurring every two to three years. Natal’s maximum temperature shows a slight upward trend, while São Paulo’s shows a slight decrease. Minimum temperatures are relatively stable in both cities. Rainfall in Natal is concentrated in abrupt peaks, whereas São Paulo’s rainfall is more evenly distributed. Fig 4 demonstrates a strong seasonal pattern in dengue infec- tions for both cities, with peaks coinciding with the rainy season. We used a negative binomial model to analyze dengue infection counts in both cities. Model selection involved itera- tively adjusting a full model, initially containing all independently and significantly associated variables (excluding average annual temperature and number of rainy days due to collinearity with minimum temperature and total rainfall, respec- tively), until a satisfactory predictive performance was achieved (Table 2). The final model significantly outperformed the null model (ANOVA, p < 0.0001), with a lower Akaike Information Criterion (AIC) (210.3 vs. 300.5). Minimum temperature

showed a positive association with dengue infections, while maximum temperature and total rainfall were negatively associated. Fig 5 illustrates the relationship between heatwave days in a week and reported dengue infections in São Paulo. Natal experienced no heatwaves during the study period, so this analysis focuses solely on São Paulo, where most heatwaves Fig 3. Time trend for dengue infections, maximum and minimum temperature, thermal amplitude and rainfall in Natal/RN, Brazil, 2014–2023. *The years of 2020 and 2021 were excluded. https://doi.org/10.1371/journal.pone.0334838.g003