As Western Europe faces a severe heat wave, scientists are investigating how extreme temperatures impact our brains and minds. Research suggests that heat waves can lead to irritability, violence, and decreased cognitive function, with children and people with mental health disorders being especially vulnerable. The effects of prolonged heat exposure on the brain are still unknown, but studies indicate a correlation between rising temperatures and worsening mental health outcomes. Why it matters: understanding the link between heat waves and brain function is crucial for developing strategies to protect vulnerable populations and mitigate the devastating consequences of climate change.