Climate change has increased droughts in recent years, damaging forests worldwide. To better understand which forests are most at risk, we analysed data of dead trees across Luxembourg during the 2018-2020 droughts. We found that tree death was strongly linked to nearby dying trees, especially in conifer forests, suggesting the spread of bark beetles, and that taller forests were more vulnerable. These findings can help guide forest management and make forests more resilient to a drier future.