The objective of this study was to verify and test the association between concern and negative emotions about climate change and depression, anxiety, and stress in students in Rio Grande, Brazil, before and after the 2024 extreme climate event. This is a quantitative study, with before and after measurements, with a single group. The questions measured the outcome: “Are you concerned about climate change?” and “Do you have negative emotions about climate change or thoughts and feelings that bad things could happen to the planet because of climate change?” The DASS-21 measured mental health. Adjusted analyses were conducted using linear regression, with results presented in beta coefficient and 95% CI. We observed an increasing concern (p=0.004) and negative emotions about the climate (p=0.019), depression (p=0.047), anxiety (p=0.043), and stress (p=0.010) symptoms from pre- to post-event. The depression score increased significantly in those who were concerned about climate change before and after the event (b=4.64, 95%CI=1.91; 7.38; p=0.006), as did depression and anxiety scores in those with negative emotions about the climate (b=5.11, 95%CI=1.59; 8.62; p=0.015; (b=4.43, 95%CI=1.28; 7.78; p=0.028, respectively). It is concluded that the students assessed increased their concern and negative emotions about the climate and deteriorated mental health after an extreme event.