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 7 / 13 lasted 1–2 days. We observed a reduced risk of dengue infection with increasing heatwave days (1–5) in a week. A single heatwave day was associated with a 70% reduction in risk (RR: 0.30, 95% CI: 0.18, 0.49). The risk continued to decrease with more heatwave days, reaching RR 0.09 after two days and 0.006 after five days. The risk reduction appears to pla- teau after three days, with minimal further decreases observed for 5–7 days. All relevant data for conducting this study are included in the Supplementary Material (S1 File). Fig 4. Seasonality of dengue infections in São Paulo and Natal, Brazil, 2014-2023. The blue box represents the rainy season. *The years of 2020 and 2021 were excluded. https://doi.org/10.1371/journal.pone.0334838.g004 Table 2. Test of model effects and parameter estimates for the final selected predictive model for dengue incidence in São Paulo/SP and Natal/RN cities, Brazil. Variable Estimate Std. Error p value RR Maximum temperature (ºC) − 2.7 (- 4.3, – 1.1) 0.81 0.001 0.97 Minimum temperature (ºC) 1.8 (0.5, 4.2) 0.76 0.001 1.07 Thermal amplitude (ºC) 1.1 (- 1.3, 3.5) 2.98 0.356 1.03 Total rainfall (cm) − 4.7 (- 9.7, 0.2) 2.56 0.005 0.95 https://doi.org/10.1371/journal.pone.0334838.t002